They are similar to class lessons where you will have a few days to post your roleplay solution.
We are setting up some rubrics to help score that deal with writing style, creativity of the solution, etc.
Yes, there will be non-champion challenges too!
We currently do not know the days yet, but you should be ok! The tournament will start on July 14th, and I don't think we are going to do a champion challenge right away.
If you feel you will have enough time to type up a roleplay post in your spare time, then I don't see why it would be a problem. Think Wayward Squirrel or NNN for what to expect. You'll have a few days to post solutions.
You are allowed to have more than one character, but only one of your characters will be considered the champion.
Hopefully that helps answer some of the questions you guys currently have. I am planning on reiterating all of this and expanding in an info/rules/FAQ thread as well.