The first thing I would do is to look for any shiny spots that would indicate a point of contact. You can also try putting a small amount of grease on anything that looks like it might be close clearance as the suspension moves through it's full range of motion and see if you get a grease smear. As for ride height all I am going to say is that any new spring or re-arched leaf spring will tend to settle or take a set over the next few months. This is true for coils, torsion bars or leaf springs so don't be surprised if the car sits a little lower in time. In so far as squeaks are concerned I've found that you're much more likely to get squeaking from polys in the UCA's than you are in the lowers. I still use rubber in the lowers myself, but I have used poly on the lowers before and didn't have any problems with them.