Laterite works fine - it's just messy if you like to gravel-vac. I've
never added more laterite to a tank - maybe you would have to after
many years. Start off with some fast-growing plants like Hygrophila,
Rotala indica (or rotundifolia), Bacopa, valisneria, or saggitaria.
Swordplants, anubias, and crinum are easy too. Add Cryptocorynes
later, once there's some nutrition in the gravel. Avoid the really
high light plants.

I have ordered from http://www.aquariumplants.com/. They have some
good assortments so you can try a lot of plants.
http://www.thatpetplace.com has nice plants too, and plant packs for 55
gallon tanks.