Okay, on /follow. Movement will break it. Casting usually does not, it will just interrupt the casting if you move. Jumping does not. Doing actions will if the guy has to move to do it, even just a tiny bit (skinning, mining, looting, etc). Channelling spells will break follow. Melee attacking, even if you NEVER move a micron, will break follow. Being too far away will break follow (but you can see that on your mini-map). So check to see what the alt is doing when he breaks follow. If he just breaks follow for no reason, you are probably doing something to trigger it and not realize it.

I almost never target mobs or players with my alts. I just focus my main and my alts use:
/cast [target=focus-target] DPSSpell for DPS
/cast [target=focus-target-target] HealSpell for healing

It makes so your alts attack whoever your main has targeted. They don't have to have anyone targeted themselves. They also heal whoever has aggro. It doesn't matter if it is your main or not, they heal the person the mob is beating on.

I use an addon called Multibox to help. http://www.dual-boxing.com/wiki/inde...n:MultiboxerV2