We have a 10g barebottomed tank with a cave for some cover and a few floating plant clippings, just because they're lying around. Barebottom is best, as you don't have to worry about anything in the gravel, and if necessary, you can easily break down the tank and bleach or sterilize it. It's also much easier to see the fish, and there's no problem with the "did it die or is it hiding" questions.
A heater is really important, as you often need to raise temps, etc. We have an airstone in there too, just to make sure it's well oxygenated if we need to medicate.
We use a filter that has the same type of filter cartridge as other tanks we have. This means we can add a "cycled" filter pad very easily. You should be able to add carbon to the setup or take it out completely, as necessary. Generally, old carbon won't remove meds anyway.