Watts does not matter...lumens is much more important. You need 100 lumens per gallon minimum for low light plants. If you can get the PAR reading on the lights, that would be even better.
Java fern would be an extremely good beginner plant, and the egeria and moss would be almost as good (the latter will do poorly in a tropical tank, though). Cabomba is infamous for being fickle, and the hygros, rotala, and bacopa are not quite beginner plants but should be no trouble once you have experience with other plants. I don't know much about the others.