I always thought T-cut was an abrasive, like brasso, it has tiney particles in it that polish out the larger scratches, bit like a liquid piece of wet and dry paper.
as for cleaning i had good results from Meguairs wheel cleaner, spray on 1 wheel leave for 15 seconds wash with water, jobs a goodun. don't do all at the same time, as left it could discolour wheels.
used sensibly, does no harm at all.