He's asking for a class, not a race, at least that's what the title suggests - in which case, romances and such wouldnt be a problem, as they simply wouldnt be included in the droid's class quests.
As for the droid being a companion rather than a leader... that's debatable, but you're right in that it doesnt make much sense for humanoids/aliens to follow a droid as companions. The obvious fix for this is to give the droid class a bunch of droid companions instead of 'living' companions.
I do think it'd be an interesting class to play, though.
I think that's where the story element comes in.
At first, maybe your companion would just be another droid or maybe a (crazy) mechanic who believes droids are the future. And then slowly, but surely, people start realizing how competent you are as a leader despite being a droid.