Not at all. Imperialism should be a thing of the past, not our foreign policy.
If it serves our interest, yes.
I would argue that, because this isn't a game of Diplomacy, our interests regarding foreign policy should be centered around peace. Starting wars is obviously the worst way to do that. Therefore it would never serve our interest unless they're attacking us.
Starting with the British royal family, yes.
THat's sound like a wonderful idea, when they can get a Cameron as president instead, a aristocrat who have even less connection with the average Brit than the royal family and he's even family.
I'm pretty sure he was talking about the royal family in 1776, not 2015. I might be wrong on that, though.