A: It's a matter of personal preference, but most experts agree 45 degrees is a good start.
But let's be real, it's not like it's rocket science. Just eyeball it.
A: No.
That would be very bad for the cat.
Why Not to Put a Bucket on Your Cat
A: Only if you enjoy watching water slide down a hill of doom.
But hey, if you're into that sorta thing, go for it.
A: That's just meta, man.