The zero distance is up to you, but I zero all my rifles in at 100 regardless (to include my .260 Rem M5). In theory there is a slight advantage to sighting in at distances further than 100 if you're going to be rapidly shooting targets at extended ranges (i.e. it takes less adjustment to hit at 500 yard target with a 200 yard zero than it does from a 100 yard zero). Practically speaking though, you really won't realize the advantage unless you're shooting a timed comp etc.
Regarding the bore sighting of the rifle, it's typically easier to do at 100 yards vs closer in. Separate the upper from the lower, and pull the BCG/Charging Handle. Look down the bore and get your target perfectly centered while you're looking down the barrel. Then, without touching the upper look through the scope to see where you are in relation to the sight picture you have looking down the barrel. In most cases (at least with picatinny mounts/rings) you should already be relatively close. If you need to adjust the, it'll be helpful to have a second pair of hands close by to hold the upper in place while you make any adjustments. The goal here is to get the two sight pictures (through the scope, and down the barrel) to be as aligned as possible.
You can absolutely bore sight closer if you want, but it won't affect the outcome; at closer distances it can be more difficult as the target (depending on the size) will take up more of your site picture down the bore.
That said, ARs with picatinny based mounts are usually very close to aligned out of the box (within 0-12" in any direction at ~100 yards). Assuming this is a new scope and you haven't been randomly dialing the knobs without returning your scope to zero, you can probably just mount the thing and start shooting at 100; it should be pretty easy to tell where you're hitting; then make the necessary adjustments.
Edit: Just looked up that scope; you'd also want to setup your zero stops immediately after getting your rifle sighted in at the range you want. Just know that with a setup like this, you shouldn't be holding for elevation/windage; you'll be dialing your elevation adjustments into the scope, so the discussion about "what distance to zero" is different than folks talking about "battle zeros" and whatnot.
It's also probably smart to leave your scope power turned down while you're firing the first few shots. If you can see the impacts through the scope, the FFP reticle should tell you exactly what windage/elevation adjustments to make.
This video will demonstrate the concept, only you're doing it on an AR vs. a bolt gun.
HOW TO BORE SIGHT A RIFLE