GS,
Have you done any spins (at alt of course) in the 172 ?
If not, find an instructor who will demonstrate and teach you how to recover from one.
I fly 172's and it is actually fairly difficult to get them to spin intentionally, much less accidentlally.
>Whilst on the subject of slipping turns: I fly a cessna 172, and if high on finals for any reason, often use crossed controls to lose excess height. (Please note that I don't do this in the turn onto finals, but when the wings are level).
Were you not taught slipping turns?
>I find this effective, but again, is there any danger of spinning?
Again, the answer is to go up with an instructor and at altitude, experiment with slipping, slipping turns, even *skidding*.
The goal is to know what the plane will do under different conditons of flight, so that you can avoid being in a situation that you've never seen or experienced.
I.e. don't try someting that you've never practiced !
Mike