There are too many ways to exploit such a system, espacially if the amount of coins distributed is split fairly between all projects in the first step.

Don't be lazy! ;) Surely we can find ways to automatically stage in projects so that the odds of a bad project being fully included is minimal, and the few that get through are still able to be blacklisted / greylisted. We just have to be willing to think about how to do it. Enumerating potential exploits is a good way to help come up with a system to prevent them, so if nothing else doing that would be helpful.:)

Also giving more voting power to possible bots who neither crunch nor bought gridcoin is a possibility to attack the values of this coin

I think you maybe misunderstood something, because nowhere did I suggest giving anyone more voting power.:)