You would definately have to cover the cleaning yourself - no matter how clean I've found tenants, they have never left a property in a condition I would consider fit to let (ie - eat your dinner off any available surface......I think it is the least you can provide to a new tenant).
Paint off the wall is different & it wouldn't be normal to repaint after just 9 months. But if you still have some of the paint, you'll cover up the damage in jig time (you probably won't have to edge - just use a small brush for the affected bits & then use a roller over the bulk of the wall - it will look like new).
Sometime the hassle & stress of trying to chase these things up aren't worth it, even if you are in the right. You could try being very clear about what is allowed on the walls (blue tack is normally ok with paint) and if you do want to be able to recoup of this type of damage, you should have a note in your contract saying nothing to be added onto the walls - I have this but it is more to prevent people from drilling into the walls, tiles & doors.