Was giving parliamentary representation to the American colonies seriously considered in Britain before the American Revolution? And had the British provided it, is it conceivable that the revolution could have been avoided, or were there even deeper factors precipitating it anyway?

I've never seen anything that said it was seriously considered, and this has to be understood in the context of how MPs were selected at the time.

Parliament was largely chosen on fixed boroughs, meaning that a town of 12 might have an MP where an entire city might also have one. The House of Commons wasn't even representative of England and Scotland (nor was there yet enough pressure to fix it until 1832). (Simplest source offhand: http://en.m.wikipedia.org/wiki/Rotten_borough)

As much as the colonists complained about a lack of representation and the taxation, they were no different than many other English subjects, except that they got a colonial legislature and lower taxes.