I'm not sure I totally understand this:
(1) If I have Apple automatically match my ad to relevant searches...do I not need to add individual keywords?
(2) If I did also add my own keywords does that conflict with Apple's matching? What is everyone else doing, both letting Apple Match and using Keywords?
You should use both, in separate ad groups/campaigns.
You should know which keywords do best, but you can use search match to find new, relevant keywords (i.e. use SM as keyword discovery, and comb through the search terms report periodically to find new keywords).
It won't hurt your chances of showing if the bid and TTR is the same for your search match vs your keyword.
Search match will sometimes show relevant terms and sometimes not, so the danger in just relying on it is that you can't control your ROI, because you don't control what Apple feels like matching you to.
-Gabe