Your concerns about applying updates are seriously overstated. For starters, the only updates Office would offer after a fresh install and update to SP3 are those that are still required to bring your system up to date. It wouldn't offer any pre-SP3 updates or updates that have subsequently been superseded. So, provided you download only those files there shouldn't be an issue. As for the update order, that is inconsequential in most cases; the few for which it matters will let you know if you try to install them before all their prerequisites have been met.
FWIW, you could also use the MS Slipstream tool to merge those updates into an SP3+ installation file (i.e. next time you install, use the Slipstream version to install both SP3 and its updates all in one go). For details, see, for example:
http://www.softpedia.com/get/Office-...streamer.shtml