I'm personally not fond of steamers, but in your case it may be worth a try. As far as future problems, if you allow the walls to dry sufficienty before you begin the painting process (1 or 2 days), there should be no problems at all. Oil primers have their uses, but I'd lean towards a latex primer specifically Benjamin Moore's interior "Fresh Start" latex primer (also comes in an oil version if you wish). If you question the origional paint job or have to do quite alot of repairs to the wall, then a primer is absolutly nessisary. The greatest advantage to using an oil primer is that it makes working with latex paint much easier. Make sure that you give the primers sufficient time to dry thoroughly.