well dark matter has the potential to become matter, so on the other side of that black hole it might actually be a star...who knows...itd be cool if we had technology to go into a black hole(safely).
Well, depends on if we're talking about a local or non-local universe (for all you wikifreaks: http://en.wikipedia.org/wiki/Nonlocality). We could say there is nothing between stars. But what about EM waves? We're getting them from the stars, so they occupy space. Electric fields, magnetic fields, gravitational fields?
Alrighty I'll preface this explanation with a little disclaimer informing you that I dont deeply comprehend what I say, but I understand it on the surface level. So I recently read this book "The View from the Center of Universe" which is great and really explains about space and all that jazz in sort of "lay-mans" terms picture/symbols and real life examples. Now, on to your question. So .01 percent of the universe is made of dense particles or "stardust" (That would be us...cool huh, were made of stardust) The next .5 % is made of hydrogen and helium and then 4% is made of invisible particles which we cant detect accurately, 20% is made of Cold Dark Energy and 70% is made of Cold Dark Matter. (I understand this doesn't add to 100% its theoretical; chill out) So this Dark Matter is constantly fighting with gravity (holding it together) and its own properties which make it want to expand, which is why the universe is expanding constatly. This does not affect solar systems and solar system clusters which because of the intense gravity holding them together are not pulled apart (so we as a solar system are not spreading out) to put this in perspective if one were to view from the earth in a million or so years the band of stars known as the Milky Way would no longer be visible as a swath of stars but actually just a few isolated dots near one another. One might also ask what this universe is "supported" by which i think is neat. So first a joke. So a Apprentice to a great philosopher asks his teacher A- "What is the world supported by?" And his teacher responds P- "Atlas" A-"What is Atlas supported by?" P-"He is supported by a turtle." A-"And what is the turtle supported by?" P-"My dear its turtles all the way down." anyhoo hope I was a help and I recommend to all blades "The View From the Center of the Universe" By Joel R. Primack and his wife Nancy Ellen Abrams
The space between two stars is just really thinly spread out matter... kind of like air if you're looking at earth or water if you're looking at an ocean as your "container".