I've built a lot of ar15's and only a handful of ar10"s but they are pretty much the same except for the parts available.
I really like the aero precision receiver sets, fit is nice and tight. Don't fall for the billet flashy stuff. As far as triggers the 2 stage have done me well hunting, I started with RRA NM 2-stage but prefer the Larue Mbt-2s with the lighter spring. The super light single stage triggers are cool but I shoot offhand sometimes when hunting so I like the 2 stage setup best
Fixed stock is the way to go, I've got an A2 stock, magpul fixed , Hera, and Lancer in the safe and I'm torn between the lancer and Hera. I like the grip angle on the hera cqr and you can set the length of pull with the spacers for cheap but not everyone digs the feel of it, advantage of the lancer is you can get a1 or a2 length and pick whatever grip you want, I am going to try one of the ergo deluxe palm shelf grips one of these days. Luth makes some intriguing stocks with lots of features but I haven't tried one, the magpul PRS used to be the holy grail of fixed stocks but it weight 30 oz and my lancer is under 10. I used to think weight didn't matter but I havent taken my 12+lb ar's out of the safe in nearly 3 years and I have a 300yd range in my yard that I shoot regurlarly with my 6lb guns.
For handguards I find I like slim and light for balance. I loath my Yankee hill diamond series because it's a huge diameter quad rail and heavy. I have a couple hera arms handguards, one is a hybrid the other just has a top rail. I won't get another hybrid because the rails set empty and I would rather have a cleaner gun. I also have a Troy rail that I like when wearing cloves but it is kinda sharp on bare hands, not a problem when hunting in the cold but I never reach for it when the weather is nice. The hera handguard did need clearances for my adjustable gas block but a combination of files and dremel made them play nice together.
I don't know about manufacturer on barrels because I have never bought a 338 barrel but lots of big names make them like McGowan and xcaliber. I like fluted barrels with medium weights on ar's, the heavy profile stuff balances bad without a brick tied to the stock. Get the longest normal gas system for the barrel length (mid length on a 16", rifle on an 18") and pick your length based on what you want, I find that for hunting a medium weight 16" barrel balances well and a fluted midweight 18" also makes a good offhand shooter. For me 20" barrels need something to set them on be it a bipod/tripod/truck/tree because the ar10 action is already so long before the barrel starts.
Everyone talks about heavy buffers for ultimate reliability and if targets shot back at me I would maybe think that way but for hunting and target shooting I like a lightweight bcg and standard or lightweight buffer then tune the gun by restricting the gas with an adjustable gas block. Theres no comparison between an over gassed gun that has a pound of tungsten going back and forth and one with a light buffer and skeletonized carrier bleeding off just enough gas to cycle.
Tools are easy, it's all basic except for roll pins, receiver vise blocks, and a barrel wrench. Depending on the handguard you sometimes need just a Cresent for the barrel
