What software are you using?

Assuming it's Keyclone, then put the WASD keys (and a few others like NUMLOCK, TAB and PRINTSCREEN) on the do-not-pass list. That way, the follower won't run off on his own when you move the main.

Attack breaks follow. There's nothing you can do about it. It's one of the reasons why multi-boxing melee classes sucks. You just have to re-tap your follow key after combat.