Perhaps you could help us to answer your question by telling us more.
"How could space,* which is nothing, be* finite and* unbounded"
First of all, where did you hear this quote? It looks to me like you have seen/heard/viewed two or three different theories and asked how they can all be correct.
Secondly, nobody has been to the edge of space (as far as I know,lol) nor has anyone shot a beam of light in one direction and the beam return in the opposite. Because of this, nobody can provide a straightforward answer. We can however, provide theories explaining some things. Everytime I post a theorie (not of my own) I get an email that bans me from the forums. I will have to leave the theories explaining your question to others (the moderators).
What stumps me on this question is, if there is an edge to the universe, what's past the edge?
Nothing? Then space (referring to space as a place with nothing occupying the space) is kinda nothing, so why would there be a finite space? This is beyond most of us. There is no real fact to answer this question.
Good luck on finding a straight answer