Any advice or opinions about the questions below or otherwise will be appreciated.

A friend/ instructor of mine switched his preference from a 2-point to a 1-point sling after taking a week-long course shooting an AR (NRA LEO Firearms Instructor for Patrol Rifle).  He had to switch arms a lot.
Therefore, my first sling for my first AR (bought a month ago) will be a 1-point.

Questions:

1--What features should I look for in a sling in general and a 1 point sling in particular?  What about a 2 point sling (for the benefit of others considering a 2 point)?   Why?

2--What brands/models do you recommend?

3--I've heard the terms "carry sling" and "shooting sling".  What is the difference?

(Note:  My primary intent for my AR/ sling is for taking self defense classes and practicing a the range (for fun and self defense readiness).  The only self defense situation I can imagine for which I might need an AR would be in my home.  I'm not a soldier or LEO  and I'm not taking it to town for dinner and movie.)

I have been very pleased with the Magpul MS4. It easily converts from single-piont to two-point, via 2 quick detach fixtures and a slider that allows shortening and lengthening the sling to fit your body.

With a 1-point sling you'll be fine if you wear a cup.

So I've heard.  I guess there's drawbacks to almost everything

Actually, I used one (1-point sling, that is) during a basic AR class I took.  I didn't even own the gun.

Do all slings convert between 1-pt and 2-pt?

No, but many 2-pt slings can be made to do the 1-pt switch.

Watch this video. You will learn a lot about how a tactical sling is used, 2 to 1 conversion, attachment to the weapon and what components make a quality sling.

https://www.youtube.com/watch?v=Ny5b7VXUU78

Wasting your time with 2point/1point combos. They aren't practical and the two point mode interfere with using the weapon. Get a quality two point and mount the sling from the rear of the rail strong side, to the weak side buttstock. The fitting should be fully closed you can still shoulder the gun without restriction, and opened up all the way you can switch hands.

I prefer the VTAC padded, but the VCAS padded is the other one to consider given your requirements.

Remember, slip your arm out to make it into a necklace if you know you're heading into a shooting. The adjustment feature is really just for hands on/transportation, not something you do in the heat of the moment

Not true with my Savvy Sniper sling.

I agree, while I don't use the single pt much, I am glad it's there when I feel the need.