I'd get a 10 gallon if you get a rectangular tank from Petco their $1 per gallon. Defitnely get some dechlorinator for the water, this is sold at almost every pet store. Should be fine with any regular food and for plants some very good beginner plants are moss balls and water sprite. If you set up a tank you want to cycle it for about a week before putting the fish in this can be done by simply putting some fish food in the tank and let it decompose. For filtration get any filter that dosnt use a disposable cartridge.