1) Do I need to have taken TT381 or the other Web Apps Development courses already?
Technically speaking, I don't think that's required, but I would prefer someone familiar with the course(s). Nevertheless, I've already had one very enthusiastic application from someone who has not taken the courses, but made a pretty compelling case for themselves.

2) How many hours are involved?
I suspect, like many OU contracts, no set number of hours are stipulated in the contract, but there's an expectation that you will be checking and reacting to the Café and other forums on at least a daily basis.

3) Is there a formal job description?
Since the jobs have never been formally advertised, I haven't seen a formal job description and I haven't seen a copy of the contract, which might have a job description attached. The job is roughly as I've described, but possibly with the addition of being a sympathetic ear too. The Café has a tradition of offering chocolate and other delightful things from time to time too.