Keeping in mind, that I will eventually want to reload for them, and currently have little or no real experience doing so, are any of these chamberings offered easier or harder to reload? Any problems to work around? Any idea on costs to reload for comparison? (I'm new to this)
Most of the cartridges mentioned here are pretty easy and straightforward to load for with no special considerations needed for any of them. 223/5.56 is probably the easiest for a beginner just because brass and load info is so plentiful, but there's no handicap with the other cartridges either. 6.5 Grendel cases can be formed from 7.62x39 pretty easily if you need to, and as far as wildcats go the 6mm Grendel-based wildcats are as easy as it gets - you can just run normal 6.5 Grendel brass through your sizing die and load it.
The only one I see that would present any challenge is the Valkyrie, just because the brass is less common. If you shoot a bunch of factory ammo though, just save your brass until you're ready to load your own.
Also - all of these are worth loading your own ammo if you're really interested in chasing long range accuracy. The ability to tune your load to your rifle can make a big difference in most guns.
On the topic of rifle weight - I'll agree that I prefer light weight ARs (and an AR can be very lightweight, even compared to a trim bolt action, if you want). A heavy AR on a bench or prone does shoot nicely though and is no handicap if you're not carrying it around much.
I recently built a 6.5 Creedmoor AR for a friend that was configured similarly to some of BSA's rifles above but slightly lighter - .750" straight profile 22" barrel, lightweight Leupold 4-12x, and a PRS stock. Final weight on that with an empty mag, no bipod: 13.6 lb.
My own 243 LBC has a 24" standard profile barrel, 10x SS, and Magpul ACS-L stock; it came in almost exactly 10 lb. I consider that one a bench gun; my preference for a walking around AR is more like 6-7 lb.
