I have a 60 litre tank, and I want these fish (see details) is this possible? Which ones are compatible?

Converting from cold to tropical, the only thing you have to do is add the heater you are buying, and make sure the water is warm in the mid 70s will do before you add any fish, sounds like the fish you have chose are good, the puffer may take time to settle, and for the first week or so expect it just to be swimming up at the gl all the time. To be honest they can be nippy for a community tank, but having said that i I have kept them in one myself.