I live in Williamsport, PA. So about 5 hours from Philadelphia.

So this is what we should use for substrate? http://www.joshsfrogs.com/abg-mix-4-quart-1-gallon.html, and just 1"-3" of it?

As for heating, would we just use an under the tank heating pad on the bottom of the tank? Or do you think they would be ok with just room temperature as long as it stays been 70-80?

I'm guessing by 12/12, you mean 12 hours of light a day? That shouldn't be a problem, I have spare timers we could use. Do they require any specific lighting, like UVB? Or does the bulb need to be a certain wattage?

They don't need a water source, but could we use something like this http://www.exo-terra.com/en/products/waterfall.php in the tank, or would it be unsafe for the frogs? I'm only asking because I know my coworker is going to ask haha.

Where do most people get their flightless fruit flies? I think I've seen them kept in containers at PetSmart, but I'm not sure if that's a safe place to get them or not.

The microfauna should be no problem at all. I have springtail central in my hermit crab tank, and I didn't even have to buy them haha. As for the isopods I know quite a few hermit crab owners that breed and sell them.

This might be a silly question, but can different species of dart frogs be kept together, or are their species that come in different colors? I know my coworker would like to see different colors in the tank if possible.