I've run Lapua, PPU and Midway's brass. Honestly the quality of the last 200 of new Lapua brass I got sucked. I ended up doing almost as much prep work on it as I have done with the other. I saw no change in group size or velocity with either the PPU or the Midway. Some of the PPU flash holes were off center but did not affect anything. No matter what brass you get you need to FL size it and it helps to have bushing dies to get your neck tension to where you want it. I run 4 thousandths tension. If you are really going for ELR everything has got to be spot on. I do full prep on all brass including straightening the necks with a mandrel, FL sizing, flash hole debur and primer pocket uniforming. you're going to need a good method for determining your OAL Giraud makes a great headspace and ogive attachment for your mic.
Bullets are a toss up. I run Sierra 300's but Barnes has some new stuff out there, damned expensive.
Get a good muzzle brake and a good stock.
I wish I could find a good place within decent driving distance to stretch a couple out.