Yeah, on a downhill slope it'll downshift a gear to maintain speed even if you aren't on cruise. I'm not sure how it's attempting to figure out what speed you're wanting to not go over, but if you aren't expecting it to do that it certainly might seem odd.
As for the bump steer, sure getting the pressures right might help make it skip a bit less, but you might want to ponder an alignment to ensure your front and rear toe are correct. Mine were off from the factory, yet 'within tolerances' according to the dealer
