The best advice any of us can give to a prospective new shooter is "Go to a match." All the reading, either on the internet, from magazines, or even the few books pales beside going to a match, seeing the equipment, seeing the target, seeing how people shoot.
From Iowa, I suspect the closest 1,000 yard matches may be Minnesota. Maybe Missouri. Depends just where in Iowa you live. 600 yard ranges are a bit easier to find.
As to your .338 LM: well, take it, unless you also have a long-range varmint rifle. Strange as it may sound, a 6mmBr that can shoot 95+ grain bullets will likely stand you about as good, esp. at 600 yards. And if you call ahead, it's fairly likely that a loaner rifle can be made available.
A brake that directs gasses rearward is strictly prohibited by most rules. But I'd not spend any money on either just replacing it, or buying any new equipment until you've been to a match.