MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
X and Y motor mounts actually make the slide adjustable as they clamp around the rack. I use some silicone grease which seems to work best; I tried some oil but that was worse. Here's a pic of the X and Y axes on a partly built Dollo: https://www.dropbox.com/s/5erg4vkb8fcwiih/2018-02-25%2014.47.52.jpg?dl=0.
There's bit of slop when janking the carraige with hand, but during printing it's not a big problem as the motors weight the thing down. Still, also due to the use of rack and pinion, there's some artifacts on the prints so it's not the best quality printer, but good for quite a lot of things.
For z I just use long printed rods (50cm on the larger version) and printed slide. Older version of that thing: https://www.thingiverse.com/thing:2613202