Thats an awesome wee tank, and a great price too! I've never seen them before. I've been looking at making a tank like that with a false wall, only bigger.
-Lighting is a little low, you might be able to get away with mushies. I have 36wats in my 34L and I only just get away with that for my zoanthids.
-BB Is definately easier, the amount of crap that collects on the bottom of my nano is annoying, and that was just live rock and corals! I have to siphon 2 x week.
-I change 30% a week, no skimmer, and I have 1 fish now. I would wait until your rock is well cycled though before adding the fish.
-The more surface movement the better
-Stay away from sponges, they will only bump up your nitrates. Let your rock do the work, though a little filter wool can be handy, and maybe phoszorb. Haven't tried it myself, I used the stuff Green-X that is now sold by fluval, but didn't really notice much difference.
HTH