I just read through the playing manual twice and only one question remains: When fighting neutral armies to conquer their capital, they do fight back, don't they? So they get a defending dice roll as well. Who rolls for them? And do they gain the same boni for the capital as well? Thanks in advance for clarifying this.

I believe that they do get the bonus dice...One of the other non-attacking player gets to roll for the neutral armies (^_^)

I also think, that the neutral capital get this bonus of five dies, and any player other then the attacker may roll for them.

But I'm not sure, who decides, which units are lost, when the neutral player roll some hits. For instance the attacker comes with 5 mechs 3 tanks 3 bombers and 2 fighters attacking a neutral capital with a tank. Then the neutral player may roll 6 dies (five for the capital and one for the tank), rolling 2 hits.

Who decides, which of the attacking units are destroyed? Accordingly to the rules, it must be the fighters before the bombers and the tanks before the mechs, but are tanks and fighters are equaly destroyed or can the "defending" player chose?

I'm not sure about this.