3rd party focus screens offer more and useful options, such as a split prism with microprism collar, that can facilitate MF. Canon's is just plain matte. However, some 3rd party screens can affect metering (so does Canon's, but there's a C.Fn to compensate, and that can work for 3rd party screens, too). Also, some screens prevent the AF points from lighting up.
I use an X-rite i1 for calibration, works well. I don't know that one does better than the others, they're all calibrating to the same standard. Some are faster, but the end result should be the same.