RE: practise at what ranges
For my hunting rifles, I practice 300 yards. Its as far as I want to shoot at most game. If I doing crop damage permits, I will shoot farther for practice, but if its a nice rack deer, I will wait until he gets within 200 yards. But I like hunting the big boys in the thickets, and rarely have to worry about shooting past 30 yards. Moose hunting, I will take a 350 yards shot depending on the conditions.
Target rifles, 500yards, still trying to graduate from that so I can move up to 800 yards.