Laundry List – Items Needs to migrate

We currently have 7 websites hosted with a proprietary CMS provider. We currently can’t get access to our own data or source code. We are sick of these guys and want to move all 7 sites to Word Press.
What do we need to get from these guys to make the transition as smooth as possible. There will be some amount of time during migration where we will need to keep this site up. We want to be stealthy how we ask for things. These are bad businessmen and will likely sabotage our sites if they find out we are jumping ship.