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.
The problem with the none flat bottom might depend on this model. There are other comments here that also point to it. Maybe it was not the best choice to start with, nevertheless these models are nice. The rest seems to be ok. If the ring still is not strong enough you cold use higher infill and/or more 'walls' in the slicer options to get the ring solid