It's a mix of sand and potting soil with a bit of cocohusk mixed in. It only smells if I put too much food in, or food that gives a bad smell. Keeping it watered and damp (at least on the food side) the soil bacteria help decompose the stinky stuff and it is more of a outdoorsy smell.
The morios do pupate but the population of beetles seems low typically. They dont like to pupate in very crowded conditions, but use wood and stuff to burrow into and pupate.
I don't use egg crates, but some branches, tiles and other "debris". The bugs cluster under things and the smaller ones like to burrow.
Anything smaller than 1/2" is tricky to gather since you need so many per meal. Over that I just pick them out, flipping logs/tiles if I need too. Supers come up to the food or when I add water and also cluster under tiles so are easy to collect. I even dig around for tiny super for my betta fish.
My setup is in a 20L
http://thelizardmadness.tumblr.com/post/163447355673