I think my bolt-on SG (possibly my first electric) was a Harmony(?). A buddy with rich parents who paid for a custom neck-thru SG (not set neck) for him took pity on my poor ass and gave me a set of PAF-ish pickups out of something nicer.. It was lightweight, looked cool with the traditional SG inlays, and inspired me to play frequently. The bolt on heel wasn't too bad since SG's we're so thin to begin with.

I just want to clarify some confusion about neck shape vs fingerboard radius.  

Neck shape is how the neck feels in your hand, from a D/Flat D (thin), vs C or Soft V (thick).  The fingerboard radius is the curve of the fingerboard on the front surface of the neck.  

Electric guitars:
Vintage Fender Tele's have a 7 1/4" fingerboard radius (smaller, more curved), while other Fender's and Gibson's will range from 9 1/2" to 12".  Jackson uses a compound radius (think like a cone shape), with 12" radius at the nut and 16" radius at the last fret where the neck meets the body.  

Rhythm players who don't solo much prefer a small radius, like 7 1/4" to 9 1/2".  This is easier to play chords, but string action has to be adjusted higher for these smaller radii, otherwise when you bend a note, it hits the next fret and chokes out.  

Players who want a "medium" fingerboard radius suitable for multiple playing styles usually choose 9 1/2" to 12". This offers easy chording and lower string action for soloing and playing faster runs or riffs.  

Metal players prefer a larger / flatter radius like 14" to 16" so they can set the action much lower without having a note "choke out" when you bend the string.

Jackson incorporates a compound radius (12" to 16" or 10" to 14") as a great way to get easy chording on the lower frets (near the nut/headstock) and lower string action at the upper frets - basically a "hybrid" approach (Fender has recently copied this on some models).  

Acoustics and classicals:
Classical guitars (nylon strings) usually have no fingerboard radius (flat or over 20").  

Acoustic guitars (steel string) usually range somewhere between 12" to 16" radius.  This is because the heavier gauge strings are a little harder push down to play notes or chords. The larger/flatter fingerboard radius allows for the string action to be set lower to help make the guitar playable with heavier gauge strings.

I have found the curved fret-boards to be irritating.  I would get the flat-style.  Especially on 1st string,
I am always slipping off the board accidentally with those curved boards.  
For clarity, I am referring to curvature perpendicular to the axis of the neck...

I would try to google/find out what equipment was used in this song:
https://www.youtube.com/watch?v=IZBlqcbpmxY
strings:
1:23
https://www.youtube.com/watch?v=rVx44W88X08

get onto one of the guitar sites and post to request some helps.  :D
https://forum.gibson.com/topic/144214-jimi-hendrix-voodoo-child-vintage-strings/
https://www.strat-talk.com/
https://www.tdpri.com/
https://www.mylespaul.com/

All fretboards have a radius, some more than others. If you're slipping off the the fretboard like you say, either you're pressing waaaaay too hard, or there's something wrong with the guitar. Could be frets, the neck may have a warp, ect...

After all my years of playing, I find that either the Jackson compound radius, or Fernandes FGZ line of guitars from the 90s with the 14 inch radius and neck shape. I cannot believe how comfortable this Fernandes neck on these models is to me. Just too bad it took me 30 years to find out.

No.  

There are 5 things to consider with regard to the shape and size of the neck.  You have confused Neck Radius with Neck Width and Neck Profile.

Neck Radius: Imagine a big wooden cylinder. from which necks (actually finger boards, but I quibble) are sliced like wedges lengthwise down the cylinder.  The outer surface of that wedge forms the fingerboard, where the frets are attached and upon which you press your fingers  to play notes.  

The larger that cylinder radius (bigger cylinder) the more "flat" the finger board is, and the easier it is to play fast runs of notes, tap, the techniques of "shredding" (think Eddie Van Halen, Malmsteen, Satriani, etc.)  Contrawise the smaller the cylinder, the more curved the fingerboard is from side to side, which most players find it easier to form full, complex chords for rhythm playing and to bend notes without fretting out on the next frets, for blues style licks.  To confuse it even more some necks have a "compound radius" with more curve up at the top next to the nut and flatter down next to the body, as if instead of being cut out of a cylinder, it were cut out of a cone.

The next metric is neck width - pretty self explanitory - it can be wide, or fairly narrow.  Shredders tend to wider necks, but it is more critical that the player's hand fits it, can reach comfortably without being too cramped together or having to stretch too far to make chords.  Only way to know for sure is to try a particular neck, wich is hard to do if you can't play yet.  A good salesman can get you in the ball park by looking at your hands - finger length, flexability, finger pudginess or lack thereof.

The next metric is neck depth, also pretty self expainitory.  How far from the the center of the back of the neck to the center of the top of the finger board.  Some players like a big fat neck licke a softball bat - theses tend to be either people with very big hands or those seeking the absolute maximum of note sustain by adding as much mass to the neck as possible.  Shredders tend to like thinner necks.

The last is neck profile.  Imagine cutting the guitar neck across with a table saw.  Some necks would look like the letter "D".  Some owudl look like a letter "C" or "V".  This is basically a descriptor of the shape of the back of the neck in your hand, and so you will hear terms like "shallow C" or "deep V".  FInd the one that fits your hand and feels the best.

The last is Scale Length  Essentially this is how long the distance is from the bridge to the guitar nut at the headstock.  A longer scale length gives you more room between the frets for yoru fingers, but also requires more tenion on the strings (for a given string diameter) to tune the strings to concert pitch, wich makes them harder to play.

For example, my Fender Heavy Metal Strats have thin shallow C profile, a 15" radius, a slightly wide neck, and a 25" radius.  (THis can be an issue as hardware such as locking nuts, bridges, etc.  will need to be close to that radius, or adjustable to close to that radius by filing, shims, or adjustment screws or else the hieght of the strings above the neck will have to be larger to make it playable.)

Mostly correcxt, but ... its complicated.  
'
Bolt on necks are very adjustable - you can install tapered shims to change the neck angle, and some even have an adjustment screw where you can loosen the bolts and change the neck angle.  Also you can "tune" the sonic response of the guitar by using different woods for the body and neck.

Neck-Thru body  guitars are somewhat rare adn expensive.  In this case the neck is made out of a long piece of stock and continues down through the body of the guitar, with no joint of any kind connecting the neck and body.  This is the most stable construction until something goes wrong with the neck which I have seen happen.  When that happens there are only two options - place the guitar in a jig with tension and heat to straighten the neck back out and hope it STAYS straightened, or throw away the guitar.

Lastly are glued neck joints which are probably what you meant when you said neck-though.  These guitars, like Les Pauls, have a seperate neck and body meeting in a joint, usually a dove-tail, sometimes a simple socket joint, to which hide or other luthier glues are used to literally glue the neck onto the body.  While much harder to remove than a bolted on neck, it can be removed by pulling a fret and drilling small holes under the fret at the neck body joint and applying heat and steam to the joint to soften the glue. The neck or the body joint can then be trimmed or shimmed to obtain the desired neck angle, a procedure referred to as a neck reset.

This is SLIGHTLY off topic but for those of you guitar owner veterans, my guitar came with a CD booklet (LOL) on how to learn tabs and what not. HATED it. Any suggestions on videos, apps, etc?

THANKS :)

I once bought a bass on the internet. It was sold on line by a pawn shop. When I got it it was a mess, I thought a professional set up would cure it all. That was when I learned that some guitars are made that will never be set up to any acceptable degree and I had to send it back. It should never have left the factory. You want to avoid these guitars.

 Whenever I want to learn how to play a song I look up the many covers of the song and see how it's done. The Trick is finding the right guy playing it correctly.

YouTube has about anything you could want, although some people on there play things incorrectly, but even if they do it'll get you headed in the right direction.

I also have Yousician. It's ok, but won't let you just listen if you need to. It stops if you aren't playing.

Songsterr is good. It's free, has gobs of tabs with synthesized guitars to play along with (they sound like an 80s Casio keyboard, but it works). And if you subscribe, you can slow down the track, ect.