Re: Speaking of which,
My mouse had the intermittent scroll wheel reversals too, until I got a can of electronic contact cleaner and (with the corded mouse unplugged) liberally sprayed it in to the area where the wheel position sensor would be (in this model, under the left mouse button). Roll the wheel around in both directions before the cleaner evaporates, and once it does, see if that didn't fix it. You could try the same on the mouse with clicking problems too (on the other side of the wheel, obviously).
If my mouse could be opened without destroying it, I would have done so for its cleaning/repair, but it has an aluminium base plate that is riveted to... well, something, and I don't want to drill the rivets out, 'cause I may not be able to get it reattached. I had to just spray it all around through the tiny hole where the axle for the scroll wheel enters the mouse body and hope for the best.
The mouse wheel worked better for a short bit, but then the reversing returned. Another dousing with the cleaner and it again worked flawlessly, and has been great ever since, for probably five months now. Since I could not see what I was squirting at, I was not even sure if I was going to get it in the right place, but I guess it did.
The stuff I used is CRC branded "Electronic contact cleaner," and it specifically says it is plastic safe on the can (which was important as I was about to shoot it into a partially plastic mouse). Of course, there are lots of kinds of plastic, but it has lived up to its billing so far for me. I've used it quite successfully on other things, including a laptop whose touchpad buttons (discrete buttons, like the all used to have back in the day) sometimes required excessive pressure to work. It sometimes works on the first try, but just as many times, it seems to require two (but so far, no more than that). It's good stuff to have around, but be sure to use it in a well ventilated area.