1. It is quite possible for a ship to not need fuel. Our submarines don't, they use nuclear power. The ships could simply use a nuclear reactor, whic would explain why they explode so brilliantly.
2. That far in the future, they could probebly use the power from the reactor and turn it into food!
3. Again, that far in the future they probebly have Very efficiant (and cheap) recycling systems for what they breath, they could theoreticly survive forever. If they could make simulated plants (and that far in the future, they would) then they Could survive theoreticly forever!
4. Ammo, the plasma and lasers would not need any ammo, again they would use energy from the nuclear reactor, the bullets (if those Are bullets) would. However, those ships Are Very large (look at the size of the windows!) they could probebly carry enough for hours. Other, more crazy solutions, are portals to a world, teleporters to a world, or some sort of mass compresser that makes each material much denser, and when time to shoot, expands them and puts them together.