Edit :Zeetrain beat me too it, oh well.
I'm going to link you to Byron who has several wonderful posts about the planted aquarium on the parent site to this site, called tropicalfishkeeping.com. You can log in with your user name and password from here if you end up browsing around other threads to view pictures.
Part 1 : http://www.tropicalfishkeeping.com/a...um-part-34861/
If you google Nano tanks you might find some too. Mostly saltwater comes up, but you might see some freshwater ones. Or just google 2 gallon planted for some pictures for ideas.
I'll let you know that plants can add up after a while. Java fern and moss can be cheap-ish I've seen them both around $4 at my discount fish store. Moss balls are around $8 near me. Most anubias plants run around $6-8 a piece.
I do not advise you to go and buy the plants petsmart sells in the little tubes. Most of them are non aquatic plants that will die and rot in your tank.
I would not recommend any other tank mates as 2 gallons is too small. Although, live plants usually are accompanied by snails. =/
If you are looking for a larger tank walmart sells the Hawk eye 5 gallons for $25 with free shipping I believe.
It would be very hard to heat that tank. Using a light that produces heat for a heat source is a very bad idea. As when you shut it off at night, which plants do need, you are taking away that heat source. Bettas can thrive at room temperature, but they are just not as lively as they would. They are cold blooded animals and used the heat to help metabolize, so lower heat can cause health problems. I'm not sure what the best brand of heater for a tank this small is. I recommend one that you adjust the temperature on and has an internal thermometer to do so. You should still keep an eye on it and adjust it as needed for the correct temperature as the two can be slightly off. I think the Hydor Theo 25 watt is possibly small enough, but I am not sure. Tanks that small are very hard to regulate. Also most fluorescent lights do not give off a lot of heat. A fluorescent light with a 6500k rating is recommended for live plants. Byron goes over that in his little posts.
Now I'm done typing a novel, hope this was partially helpful.
I hope someone else can give you better plant recommendations too. I'm just getting started on planted aquariums and am learning myself. :)