The Basics on Dwarf Gouramis?

I deleted my other one, I had the wrong fish. Okay I'm going to get some Dwarf Gouarmi's soon. I have a 10g tank that they will be put in. I also have a 7 inch Dragon Goby as well. So how many Dwarf's should I get and whatdo they eat as well as any other basic tank care. oh and can they live in slightly brackish water?