10 gallon would be fine for a majority of fish. Even really small tangs. I QT my salfin in a biocube when I was the size of a quarter In order to get it to start eating prepared foods. A HOB (hang on back) filter will work perfect that'll take care of water movement. Just take the filter pad with carbon in it out if you plan on treating with copper. You'll need a heater and some PVC pipe appropriate size to the fish so that the fish can hide in it and feel safe. Without a hiding spot the fish will be very stressed. You can put a small low power light over the tank but it's not needed as long as it's in a room that it'll get some ambient light either from a window or your display.
The only drawbacks are that being such a small tank you'll be changing water quite often to keep up with water quality. Also be sure that you keep a close eye on the water level to maintain a consistent salinity. Swinging salinity will stress the fish. Although an ATO will save you the hassle of topping off.
Hope that helps! Keep it simple! Just be sure the tank is cycled before you add anything. Last note If you plan on putting more then one fish in the tank I would recommend separating them with something as simple as a piece of plexiglass cut to the correct size and holes in it small enough that the fish can't go back and forth.