I went the same way, knew I could get a bargain bin rifle or complete upper for cheaper than building it myself, but I don't regret it. Has been a lot of fun building it all. Since you mentioned ARFCOM I don't need to point you there on advice for how to build it
. Of course, a downside is I have not skimped on quality and now have a much more expensive rifle than I originally planned for.
Some thoughts I have on what you have listed:
Looks like that is a stripped upper receiver, so you will need to get an upper receiver parts kit (dust cover, forward assist) to go along with it.
I got a lot of Yankee Hill Machine (YHM) stuff in mine that I am building. YHM lower at the fun show in Fremont, then the rest I got online.
YHM flat top upper kit, YHM 16" fluted barrel, low profile gas block were all direct from YHM.
BCM bolt carrier group I have, have not heard of anyone ever having problems. Also got their gunfighter charging handle mod4.
Find out if you need a barrel nut and all of that for your float tube so you can lump it into your BCM order since they have parts like that. I went with a Larue free float tube so it came with what I needed in that regard. I spent a lot of time trying to figure out what small parts like that I would need. Same thing with the stock you get, check to see if it comes with the spring/buffer/tube and all that.
I just got a DPMS part kit (only thing I could find in stock at the time) and I will be replacing the grip it came with for something more comfortable, but the rest of it looks all good.
I just ordered the last stuff I needed last night for the rifle. Tijicon TR24 scope, Vortex flash hider, and a nice quick detach bipod setup.
As far as tools, the only tool I used was an "AR15 multi-tool" which has a barrel wrench on one side and a stock castle wrench on the other.
Of course, I have no idea if mine works or not yet. It should, and I'll be testing it shortly. It was a lot of fun to build it.