Have not done a frog set-up yet; but agree the white squared material is found in the lighting area at both Lowe's or Home Depot and is called "Egg Crate Lighting Panel."
IRT pumps you want to get one that has the required flow and "water head" combination you will need. Many pumps will have a rated flow at it's output. That flow will be affected as the pump has to work against gravity and lift the fluid from the tanks water level to the output above the waterfall. Also make sure the pump you get can operate at the water level you plan to have in the enclosure, some need just an in. and others require deeper water. Good luck!