DISCLAIMER: These are my opinions only, and are worth what you paid for them. I have owned or played with most of the stuff on your list.
Optic: I prefer the T-1 over the legacy M2 or ML2, crisper dot and better sight picture, in my opinion, also longer battery life on easier to find batteries. The newer M4 is also a good choice, hard to beat 8 years on a AA battery.
VFG: I like the Tango Down grip, preferably in the stubby version, but either is ok. The AFG is nice, I have some, but I always seem to go back to a regular VFG. You are pretty much locked in to one hand position with it, the stubby Tango Down grip, you can rest your pinky and ring finger on it and grasp it like an AFG, or you can use it in the thumb break hold, or broomstick hold, or whatever and you can switch back and forth at will instantly, depending on need or shooting postion, etc. I personally feel like I have more control with a VFG, YMMV.
Light: Out of your three choices, I like the X300, high lumens, good runtime, shock proof, lightweight, most durable of those listed. You could get the remote switch adapter and put the SR07 on the 12:00 rail or the Gear Sector offset mount, either would be a nice set up.
Butt Stock: I have never used a UBR, although the weight is a major turn-off to me, it does not seem to bother those who actually use it and can balance out a nose heavy carbine. I have used the Magpul CTR/MOE, SOPMOD, and VLTOR Carbine Modstock. I prefer the SOPMOD/VLTOR cheek rest, but also like some of the features of the Mapul stocks. The VLTOR Imod stock seem to me to take the best of all these stocks and roll it into one nice package. It would be my choice.
Flash Hider: No real opinion, although $150 for a non-suppressor mount muzzle device is a little silly. Makes those $100 Blackout mounts for my M4-2000 seem like a bargain.
Trigger: For your stated intent of home defense, SHTF, and range use, the two triggers you mentioned would be less than ideal. High-speed target style adjustable with set screws and what not should not be used in a serious social weapon. In the 2-stage arena I would go with the Geissele SSA Combat Trigger. Also a Spike's Tactical Battle Trigger, or standard G.I. trigger would be a could choice for your intended use.
The rest of what you have listed, no reason to spen the extra money on fancy trigger guards, the polymer MOE unit does the same thing for much less. Also, grips are highly subjective, you should try and hold several different styles and see what you like. I prefer the MIAD over the MOE, since it can be configured however I prefer, also the insert core on the MIAD is much better made than on the MOE. That said I have no problem with the A2 grip, this is not as important an upgrade as it may seem. With gloves on its hard to tell the difference, also, resist the urge to use a really big hand-filling grip as it can make reaching the safety selector more difficult and really add un-needed distance and difficulty with gloves on.
Sound like you are building a really nice rifle, have fun and enjoy!!