Before I do the iOS 7.0.2 update [...], can you tell me how to get at the downloaded copy stored on the Mac from the first device so I can then update the other device without further impacting my limit?
Your plan to keep a copy of iOS or the updater(s) around is a good one. Unfortunately, the various model iDevices each have their own and different iOS versions and updaters, so using the iPad version for the iPhone (or the other way around) won't fly. See
Download iOS Updates Once for Installing on Multiple Devices for details.
