X2 on staghorn. You can't kill that stuff without killing the plant first, nothing works. I also agree you need to reduce the photo period. Adding CO2 would also help but the photo period is the big one.
Plants can go in any time. You will have lowish light even with 2 40w bulbs so you'll be able to grow things like java fern, java moss, anubias, (those can be attached to wood or rocks) crypts, dwarf sag, maybe amazon sword, vals, anacharis