Hi Jeanie,
Yes, absolutely. The exercises that you mentioned are exactly the ones that I still find challenging. The one legged squats to touch the floor have always been one of my favorites for ski conditioning, and I can easily do 30+ on my good leg. Before surgery, I could due about half as many on my bad leg, but with more pain and difficulty reaching the floor. At this point 15 months post surgery, I still cannot quite touch the floor on that side. The lunges you mentioned are another area of weakness. Lowering from a high step is another. As part of my training I do laps up and down six flights of stairs for 15 minutes, and I have no problem walking or running single steps, or two at a time. However, as soon as I step up or down off of something much higher than two steps, I feel the weakness and instability, so I am focusing more on that now. It is worth noting that two legged squats, even with substantial weights, are no problem, and therefore do not address these issues at all, nor does biking, since these do not involve the lateral and rotational stabilizers.
Keep up the good work!