I think you can use almost any paint for the tanks, just make sure to clean them well.
I've used both spray paint and brush-on latex. I found the spray paint to be less work, but the latex may have been easier/fewer coats if I used a roller instead of a (cheap)brush. Just make sure to cover the top so overspray doesn't get in the tank.
As to the stand, I guess it depends on what sort of look you are going for, but most of the effort is going to be in prep work - sanding/filling, and using a decent primer. I think a matte or egg-shell finish is less likely to reveal minor flaws, but then a gloss finish is easier to clean so...
Also, I think almost any paint should be fine as far as water resistance goes, unless you are planning on keeping the pieces nearly perpetually wet.