Hi.
Well my traction control makes absolutely no noise when it kicks in, not that I've noticed anyway. I've never had strange sounds from the rear.
As for the lumpy steering I experience this in the cold as do a lot of members if u do a quick search. I got mine checked at Lexus, they say pump is fine, fluid good and belt correct tension. So I'm just putting mine down to not liking the cold!
As your fluid is below minimum I suggest you top it up. Dexron ii or iii is needed. Dex ii is blue and dex iii is red so just match the colour that's already in yours but it is ok to mix and match :)