I would do everything Stuart has said. But in addition you need to find out how much data loss is acceptable for the db (IN WRITING). I wouldn't change any access permission but would highlight anything about the setup that you are concerned with in a e-mail to your superiors. Send them a list of what you will do for maintenance etc. and state if anything else is required they should let you know.

Put the basics in place CHECKDB etc and leave it as that.Also state that any dbs\sql servers which are created on the estate should be verified by the DBA before they go live. I had the same situtation last year and it drove me crazy. So I setup a task to sweep the network looking for new SQL instances of servers.

I think it was based on a OSQL command using the -L switch if I remember correctly.