My hair grass is doing very well with just over 2 wpg. i found that the trick, at least in my tank, was to brake up the clump of grass into several smaller bunches and plant them near eachother. The areas fill in much faster that way.
For upgrading my lights I just bit the bullet and bought a Coralife Aqualight. It was just over $100. Not super expensive by any means and i think it has made a big difference. Looking forward to putting a 6700k bulb in (as opposed to the 10000k). Not sure about the reptile light (do they have lense to keep evaporation and condensation away from the fixtures?).