no, greg, this is not the way pdf versioning works.
at least not in a linear way.
different pdf versions support different features.
but, it's true, in the same family of versions, higher numbers mean that all of the lower version features are supported and some more on top of it.
you should really make sure that you pick the version your print shop is asking for and that you stick to the features that the given version supports.
and be warned, that sometimes print shops have the bad habit of asking for a given version and add further restrictions.
(most of the time, until you're 100% sure that your printshop will manage correctly the transparencies don't use them (or use them in an almost visible place for testing them : - ))