i think you should do what you want, it doesn't matter what any of us think it matters what you think and want

Mixed wood is horrible for some people to look at. I'd paint the stand personally. Oil Prime then paint. You will be happy

If the rest of your furniture is dark, the aquarium will stand out.I would either stain it to match the rest or stain it to match the color scheme in the room you are planning to place it.All of my furniture is very dark as well, but the true colors vary.

Depends - sometimes a nice juxtaposition is nice. Try it and see. Maybe you want the aquarium to be a focal point. Black and white go well together. It's the contrast that makes them sinq! Put the aquarium in place and stand back and look at it. Imagine it filled with moving, living creatures. A nice, clean aquarium with it's vibrant colors and that crystal clear water is a reaaly beautiful thing to look at. Also, however, think about the up keep - when it gets dingy it's awful - so, if there is a possibility it might be a couple of weeks between cleaning, you might want to make it darker to distract from that. Make sure you have a really good filtering system. If it's a ten gallon tank, make sure you have a 20 or 30 gallon pump at least. This will cut down on maintainence.

So, the question is, Is your aquarium the focal point of the room, or an accent. Once you answer the question, everything else will fall into place.

I'm assuming that the stand already has a finish on it. If so, then don't stain it -- stain should be applied to the wood, not on top of polyurethane (at least if you want the stand to have a similar finish to the rest of the furniture). Either, prime then paint it -or- leave it.

Cheers!