I chose Roto-Choks over X-Chocks, so I cant help you there other than yes, you will want a pair of them.
For leveling, I went from wood blocks, to strips of horse stall mat, to Andersen Levelers. Andersen Levelers ARE all they're hyped up to be.
I did find that when I only need an inch or so to get level, I prefer using something other than the Andersen's. I cut one of my stall mat strips into a few small pieces about the size of those plastic lego blocks. I can use the rubber block by itself if only an inch is needed, and I can use it under the Andersen Levelers if I ever need a little more lift then they offer. The stall mat strips actually worked great for leveling and they are indestructible but I went to Andersen Levelers to save space and weight.
'04 GMC Sierra 2500HD, CCSB, D/A, MaxBrake, B&W Companion, Retrax Pro, AR Power Steps
2013 Rockwood 8289WS w/Diamond pkg
1969 Camaro RS/SS Convertible
Dad's old 1968 Empi Imp (recently recovered from under 21 years worth of boxes/dust)