Lol Tsagoth.

1. The fleet will act just like a single harvester which never waits till it is full. It will fly to source planet, spend 1 minute loading whatever is there(even if it is just 1 RU) and fly to the destination planet, spend one minute dropping off and repeat. That is if they fixed fleets. Last time I tried using fleets for harvesting they would use the source planet as the dest planet and vice versa.

2. All ships will act as combat ships when entering a battle. There are not "non-combat" and "combat" classes. All ships are combat ships even if they are probes with 0 attack and will behave as such in a battle afaik. As far as the combat tactics on which ships get targeted first that would be interesting to get an answer on. In battles I have been in before it appeared the weakest ships were targeted first so I was able to use harvesters as cannon fodder when attacking a colony.