Further to the points made by @T0NIT0RMX, I will say that I rarely add breaking changes to anything in Cabbage. We just updated the look and feel for widgets, but one can still have their instruments display using the older style widgets. Identifiers don't generally changes between versions, but new ones are often added. Again, this won't effect older code. The Cabbage examples provided by Iain McCurdy are one of the corner stones of this project, therefore I do everything I can not to break them! So in summary:
No. Unless we happen to find a bug, which is very rare.
No. Any VST you build should function just fine in the future. If not let me know and I will address the issue as quickly as I can.