I've done a few light coffee beers and I keep it pretty simple with great results.
I've never sought out any particular coffee and usually just get a decent brand from the grocery. I've found a medium to dark roast works best for my taste. You won't extract much/if any bitterness when using whole beans. I don't get too picky, but you may want for a brewery.
I usually do around 1oz/gallon. I've done whole bean and I've also pulsed them a couple times in a coffee grinder (literally one to two pulses). I dump them loose in the primary after fermentation is complete. Let it steep for a week, and cold crash. They'll drop out like hops.