You generally have to distinct between bitmaps you create manually (bmap_create, bmap_createblack, Panel Definitions etc.) on the one hand and bitmaps that are created automatically for textures for you level or your entities. When they are created automatically they will be removed automatically as well on a level change. When you created them yourself you have to take care of removing them any time you see removing may fit your needs.

1. They are freed from memory. You won't be notified about that. Exactly. Don't store pointers to bitmaps that are automatically freed in a pointer.

2. Nothing. Take care that you don't loose the pointer to such bitmaps or they won't be accessible any more.

3. Nothing