What do they do within the game? I'm pretty sure only the R1 series has started to be implemented, also what is their intended function?
I'm pretty sure from a canonical point of view they allow hyperspace travel for ships with no nav comp(like x-wings), and also do some inflight maintenance, but in combine x-wings already have hyperspace.
If you have a droid with an appropriate piloting skill in your cockpit, the droid will take over controls while you nip to the toilet in your docked vehicle.