4) I think it's 8,9,11,12 kg scales... I gotta go to work though, so I only tested it to liek 15 (and 30 once). So let me know if I got it.
5) Choose six marbles and measure 3v3.
If one pile weighs more than the other:
Take two of those three marbles and measure them. If they're equal, then the odd one out is the heavier one. If one weighs more than the other, than it's the heavy one.
If the 3v3 weighs the same:
Weigh the last two and the heavier one will show.
6) 9*9+9+9+9/9
That valid?
7) Twelve days?
8) 33%?