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.
Unified Z axis mount helps ppl easier to align rods and leadscrew, but segregated one is more forgiving.
About length of the bolts, I don't remember exactly. Usually I keep various lengths in stock and re-stock if any runs out.