Thanks for your post. It is very inspiring. I have been having problems with some of my lifts - particularly squats and deadlifts and I think mobility is the problem for me too. I think this part of training is often overlooked. Without proper mobility you can't stretch the muscles properly and so in effect your gains are severely reduced.
As far as squats go , I always do heavy sets in the 3-5 range first followed by a squat variation in the 8-10 rep range for a few more sets. If you dont have a foam roller you should get one.
Its helped me a lot for lower body workouts.
I like to warm up my it bands before squats and focus my warm up sets on speed.
What are you having trouble with?