1. yes, you will go to DEPOT
2. You won't be coming in as an E5, especially since you want to change ratings
3. Yes. You'll graduate DEPOT as an E3
4. I don't think so. Be aware ME A School wait list is closed until further notice. It was closed for six months recently, reopened, and then closed again(back in May, I believe). Consequently, there will be one Hell of a backlog when the list is eventually reopened. Reservists are still able to go to ME A School, as they do not go on a wait list. THey are given an A School date by their recruiter.
Something else you need to be aware of as a prior service guy with 8.5 years in, is something called High Year Tenure. This is a career management tool. It keeps people from sitting in one paygrade for too long. Essentially, if you haven't reached a certain paygrade by a certain point in time, you will be processed for separation. I think you'll be cutting it awfully close due to your prior TIS. You definitely want to get clarification from a recruiter on this issue.
The two suggestions I'd have for you:
If you want to be an ME, go in the Reserves. You won't be able to go into MSRT, however, as there are no Reserve billets there
If you want AD, go into your former rating (in the CG it's called HS). Because you have significant experience, you *MAY* be able to get an A school waiver. Your recruiter would submit a Rate Determination Package to the HS Rating Force Master Chief outlining your training and experience in the Navy. The Rating Force Master Chief could then authorize you to come in as an HS3, with an A school waiver. Stuff to think about