this is what I would do.......
I dont know what kind of shed you have, but here is what I would do to the crappy sheds we have around here in NC. Also, the modifications I'm speaking of are to keep the room as constant a temperature as possible in the mountains, but anywhere you are if you insulate correctly the room will stay at a constant temperature.
First, make sure the roof on it is good and doesnt leak. If not, fix that first. You could always compensate for an unlevel floor by mounting a level table, but the floor needs to be stableand sturdy. There is no telling the weight it might have to hold (this hobby is addictive). Like I said, the sheds I'm familiar with are crappy.
I would then seal the thing up as tightly as I could. Insulate the walls with the pink stuff and then cover it with something (drywall, paneling...). Also at this point you would need to make sure you have all electric taken care of that you might need. Insulate the ceiling and the floor as well. I dont know this for sure, but I know the pink insulation has fibers that are an irritant to humans, so I'm assuming it will be an irritant to frogs as well, so make sure to cover all insulation in the room.
Paint the walls and ceiling with some sort of water resistant paint, since the humididty in the room will probably be of a higher percentage. Also make sure any spilled water will not ruin the floor, as you will probably be spilling water at some point. My dream animal room would have a drain in the floor.
Be sure that the windows and door are sealed tightly with no leaks or replace them with good quality double paned windows or a good door to hold the temperature. Like I said, I dont know what kind of shed it is.
Basically anything to make the shed insulated and airtight will help. Anything other than this would be your preference to better accomidate your frogs. A heater if you live in a cold climate might be required. On the other hand the lights and stuff might keep the temp up ( a backup heater is what I would have!). I would stay away from gas or oil heat since this gives off fumes that might be detrimental to frogs. I also wouldnt have it blowing directly on any tanks.
Ok, verbal vomit here. I hope that answers your question. I'm going to set up a frog room with an electric heater and a small AC unit for summer use to keep the temp around 70ish. I dont know whether I'll have a large humidifier in the room or a separate small one on a timer for each tank.
Good luck!