I won't be able to answer all the questions, as I mostly deal with tree frogs, but here's my attempt, lol:

For live plants, ABG (atlanta botanical garden) mix is the norm, but Neherpetoculture.com has its own mix as well that I've heard good reviews of.

For food, I do believe that crickets would be the typical staple. The rule for size is that the cricket should be no bigger than the space between the eyes of the frog. Crickets can typically be found in any major and many smaller pet stores.

A mister system is not necessary, but to maintain humidity, you might find it necessary to hand mist with a small spray bottle that hasn't held any other liquid before.

If you have ABG mix, cleaning poop is not necessary. The poop will break down and actually add to the health of the soil. If you use microfauna, such as springtails or isopods (the clean-up crew), in the soil, then changing substrate is actually not required.

A false bottom setup is pretty simple and cheap, actually, and doing a half water/half land tank will allow you to slope the soil and make it look more natural. The idea of a false bottom is that there is a layer of what that is essentially under the soil. The water feature would just be where the false bottom does not exist, and there is an opening into that layer of water. The water level has to be at least 1/2" under the soil level to prevent bog conditions (unless you want that ).

Don't worry, details are often most important when building a tank, and often result in the difference between success and failure.

I'm not an expert when it comes to these kinds of frogs, but hopefully others will chime in.

Hope it helped.