Just to know if there's a way to stop your cast on your abobination let's say your half cast on a powertap and then you want to stop it... Anyone knows?

I've managed to do this by hitting passive pet command several times. You gotta be quick about it though.

Yeah that's what I was trying, but you know you can drag in your bar passive so it's faster I'm gonna do some testing about it.

Yes you can put the pet commands on your quickbar. I put it on the second bar and spam Alt+1 whenever I see someone else pulled my target already. The pet continues it's cast animation, but it does not hit the target.

I usually bind my pet movement to keys, that way i dont need to waste a hotbar slot on it. I have all 3 stances (aggressive/defensive/passive) bound, aswell as "follow" and "here". Go target i never use so no point.
It really depends on your personal playstyle. Me - i like having EVERYTHING bound to direct keys, while some feel better about point and click or just having the macro shorts on the hotbar itself.