1. The MP component? Level only. Like WHM's Shroud of Saints.

2. The DoTs are snapshotted when applied. Bane spreads the snapshotted version, minus elapsed time of course.

3. That's partly right, but it doesn't seem to take into account certain modifiers. Gear is taken into account, for example, potions are not. From your testing, it seems Clerics also doesn't matter.