1. Is dying allowed?
2. After getting the 5th boo on area 2 I always have low health where can I find some hearts?

1. I believe dying is "banned" in all categories, but I could be wrong. It's typically a run killer anyways due to not saving during a run.

Dying as a form of save warp is banned, but otherwise is fine. Source: I died 3 times in my first any% run and it was accepted. The rules may be more strict now but I'd probably defend you if you're running by legit means

Dying is allowed as long as you don't use it to warp forward in the game, like skipping a mirror teleport.