I wouldn't buy any plants from petsmart/petco.. they don't know what they're talking about with plants and the plants could come with all sorts of bad things.
If you want plants I would order off aquabid or highly rated sellers on ebay. The user mcgamer2000 on aquabid is very reliable. His website is www.bobstropicalplants.com
and he can answer all your questions.
The type of plant you get depends on your substrate, wpg, and whether or not you are going to have a CO2 set up.