First off, welcome to RC and welcome to the Mantis forum.
Have you read Dr. Roy's guide? It's stickied at the top of the forum. That has the answers to some of your questions.
As for setup, I'd say a 20L, at least for the tank. You need enough substrate for it to dig a burrow, and some live rock for it to dig under.
You don't need bright lights, which can actually be harmful to them.
A clean up crew is a good idea, and while you may wish it to only eat prepared foods, it may well have different ideas.
It's also a good idea to let it hunt - the raptors need to be used. One possible source of danger for a captive mantis is that it's appendages won't be strong enough, and there could be problems with that during the molt. If the appendages get stuck, then it could result in a fatal molt. Just something to keep in mind.
