Spellcasting using too much mana?

[Drawde]

I've found that when playing low-level characters, casting spells will always
use up all of your mana, regardless of how much mana the spell is actually meant to use.
However this doesn't seem to happen with high-level characters. Maybe the mana subtracted when
casting is more (2-3x) than the amount it should be, so if you have a very low mana capacity then
casting anything will use it all?

Also, with the latest 2.4 beta, is it true that NPCs will now only attack you if your account status is 0 (player)? This seems to be the case but I just wanted to check!