This is a two part question, with the two parts being mirror images to each other.
Is the ability to use the Force a requirement, for some reason, to using a lightsaber? And if so, why?
And on the other side, on Hoth, when Luke is hanging in ice in the wampa's cave, he uses the Force to bring his lightsaber into his hand. But, as best I can remember and find, the Jedi always use a lightsaber like a "real" sword and keep it in their hands (although I think there's one case in a movie where a lightsaber is thrown to cut down support for a walkway). Can a lightsaber be wielded with the Force only? For instance, when Anakin's hand was cut off, could he have controlled the movement of his lightsaber the way Vader did with the objects he Force-tossed objects at Luke in the Cloud City?
While that's two questions (that I think are closely related), another way to put it might be to ask, "How closely is the use of the Force related to wielding a lightsaber?"