How should one go about reheating pasta?
easiest way is to mix it with the sauce and heat both up together.  Usually I'd do this in a pan, but you could use a microwave.

If you have to heat the pasta up on its own, what I usually do is do it in a pan and add a little boiling water, just a couple of tablespoons, enough to stop it sticking, and keep stirring until its warmed through.  If it starts to stick add a little more water.

You could do this in a microwave I'd bet, but I don't have one.