I have been testing CSL for a while now, and we started using it on customer cars this Summer.
CSL has performed very well without EXO on top on both of my test panels (one on my personal car - 6 months old, and one on my wife`s car - 9 months old). The coating is quite hydrophobic on its own, but EXO is said to be even more hydrophobic. If water beading is your #1 priority, then perhaps layering EXO is your best bet. I will also add that a US GTechniq Rep did say he would not top CSL with EXO because CSL is harder than EXO once finally cured, so to him it was more beneficial to have CSL as the only form of protection rather than a softer top coat just to enhance beading a little bit.
As far as application goes, it is pretty straight forward. Clean, decon, and correct the car prior. Ensure you do a thorough IPA or Panel Wipe cleansing before coating. Apply CSL to an applicator (we use the CarPro applicators) and spread onto a small area. Immediately wipe off with a clean towel, then a light pass with a 2nd clean towel if needed. Work your way around the car until it is covered. You will immediately notice how slick it is as you are wiping it off with your towels. It is so incredibly slick, that you can easily tell if you have missed any spots afterwards if you are wiping with C2 V3 or a QD because an uncoated spot will stop your towel in its tracks compared to a spot coated with CSL.