How would you even get your hands on 10.7 at this point? (and I mean legally) By the time you start your upgrade next year we'll probably be seeing betas for 10.9. I don't know that you'll have an option to go with 10.7 at that point. Apple looks forward, not backward. Getting 10.7 licenses from them won't be easy.
And to answer your second question, it may in fact depend on hardware. If you're buying any new Macs since the last update this year, they will require 10.8 or higher. Conversely, some older Macs will not run 10.8 at all.
All that said, you also need to consider your software. If you have older software titles that are not compatible with 10.8, you'll need to check on them, see if a new version is out that works with it., plan on upgrades, etc.
