It seems like you're actually asking about mass, volume, greatness, and smallness, and how they interact with infinity. Or at least, you're asking about those four as much.

Anyway, a couple guesses at the answers. First, I think the volume of the infinite number of infinitely small particles would simply be infinite first, and that infinity does weird things and is not large or small in a cut and dry, referential way. So the answer I suppose would be that they infinite RATHER than being large or small.

The other more simple answer I think would be that basically 'large' is the right answer, since even if the infinitely small particles are tiny, there's still something infintesmally small that makes it a particle of some sort. And since there is something, however tiny, to each particle the infinite quantity of the particles ensures that you have and infinite positive quantity of particles, and so matter or what have you. So the infinity of the quantity of the particles wins out and makes it large, basically. Or what I said above. Or both. Or, probably neither. I'll let people with knowledge of set theory go on to refute me.