Most of the list seems GTG. I'd go 16" to 18" barrel. 14.5 will require a stamp or a permanently attached device. 16" works fine, but I really ended up liking the 18" I used for one Grendel build that my buddy now owns. Liked it more than my 20", but kept the 20" as I have a lot more into it. I have a 14.5" And have had 16", there's not much difference for me.
Muzzle device, depends what you're looking for. .223/5.56 have so little recoil I never find the need for a brake or comp for myself. Grendel is the same. All of those basically have flash hiders. 6.5 Creedmoor is the only rifle using a brake and that is a JP. It is loud, but very effective. It is one of the JP Compensators. For hiders I stay with SE Vortex or YHM Phantom. Yes they are old, but they work.
Triggers... again depends what you're looking for. Both carbines of mine currently have standard spec single stage triggers. If I was to change them; which I probably will at some point, I'll look into Rise, CMC or something along those lines. I have never seen a reason to change those and that why they still are what they are. If it comes to two stage triggers, I tried a lot of them recently. My top three are AR Gold, Triggertech and Geissele (more or less in that order). The AR Gold and Triggertech are similar so are kind of a tie. LaRue is mentioned often and is not a bad mid grade two stage trigger. I have two builds in progress. A 458 SOCOM and another Creedmoor. Both need triggers. I have a brand new LaRue MBT and have considered using it in the 458, but have thought a really good single stage might be better. No consideration for using it in the Creedmoor as i already had one in my current Creedmoor and Grendel and didn't care for it in either of those precision rifles. I sold the one I used in them off and replaced it. Another Triggertech will be used in my current Creedmoor build. If you like the Hiperfire then you should probably go with it. If not you probably won't be satisfied and swap it later. If you don't like it, you can always sell it off. If at all possible try out different triggers from friends or range acquaintances. You may find certain brands you like more and others you thought were interesting you end up not caring for. I usually let people try mine if they ask. Wish i could have tried a few out, would have saved some money and time along the way because i wouldn't have had to bother buying a couple of them.
Vortex makes some good stuff. Don't think you can go wrong there.