Ok here's the scoop

I just got back into hunting with a rifle *been using my bow, however, opening day i made a 435 yd. shot on a nice 8 pt. with my friends 270and for some reason or another that distance shot got my blood rushing more than a 20 yd shot with my bow* so im looking to pick up a new rifle.

I am an 18 yr old from Texas *senior in highschool* I mainly hunt in south Texas for Whitetail and wildhogs however i hope to travel to a friends ranch in Canada and harvest an Elk and some other animals up there. Looking for the best caliber for accomplishing these tasks. I'm looking to spend approximatly 700 or less on the rifle alone so if you have any other suggestions for rifles for me to look at that i passed on then please let me know.

Delimma #1:
Caliber - .270, 7mm *all variations* what are the differences in the variations in 7mm's?

Delimma #2:
Company - I have narrowed it down to 3 different companys and the styles im interested in from each company:
Remington SPS - Very affordable, been reading lots of good things about them
Ruger - Allweather, and the Sporter
Browning - Abolt Composite Stalker

This is my first post so i hope this was fairly well put together and if these questions are already answered in a sticky somewhere i apologize for this thread