#1
If i switch my current pickups to Blackouts which are active can i put the battery in the Trem cavity?
My Gear

Guitar
DEAN Razorback Shards
Wesley crappy cheap thing

Amps
Cheap Crappy Freedom Practice AMP 15watts
VOX AD50 Valtronix
#3
battery location should not matter as long as the leads reach. Seems like putting it in the trem cavity might interfere with your trem though.
#4
I wouldn't do it, but you probably could. Generally you want as much space as needed in the trem cavity, as there are moving parts. If a spring hit the battery and lets say idk, slipped out of the place holding it, it would not be good. Especially if you leave your trem cavity open, because that would probably result in the spring nailing you, and depending on where you play your guitar, it could be where it counts.

I'd just say put it in with the electronics or rout a hole for it, preferably the second.
#5
Has anyone else switched from passives to actives? Was it difficult?
My Gear

Guitar
DEAN Razorback Shards
Wesley crappy cheap thing

Amps
Cheap Crappy Freedom Practice AMP 15watts
VOX AD50 Valtronix