I know that they are the same! I was just using them interchangebly, I like to use both scientific and common names.
They don't eat snails, not that I know of at least. A couple good foods off the top of my head, live brine shrimp, live cut up black worms etc. You can teach them to eat frozen and maybe prepared foods eventually but it is better for them to eat live.
I think you could do 2-3 Pea puffers, but only one male. Danio erythromicron would be another option in a 10 gallon, they're very shy but are beautiful. Here's a list for 10 gallon: Stocking List for 10 Gallons