You're lucky you posted about this because with that gravel I firmly believe you're frog wouldn't last another year before a fatal impaction. And I know of only one frog expert in a store and his business is just selling frogs and plants. For a substrate, I would recommend fine coconut fibre or crumbly top soil (or a nice mixture of both). You could mix some sand in there too. The moss is probably safe, but I wouldn't risk it with Pacman frogs or Pyxicephalus.
The wattage depends on the size of the terrarium (particularly the depth). For small terraria I like 40 watt bulbs. For these frogs, I would keep it in the mid-70s during the night and mid-80s during the day.
With a varied diet you really shouldn't have to supplement this kind of frog with anything other than calcium, and you should only be doing that once or twice a week for a young frog. If the frog won't eat it, let him go without food and try again next time. "Hunger makes good sauce".
Thank you. However, most of the frogs I photograph do not belong to me.