The problem w/adding the coffee before you bottle is you have to GUESS how much to use. Yea, you can follow a recipe, but will it be to YOUR taste or that of the guys who came up w/the recipe? So here is what I do and have done it three times already and will be doing another 10 gallon extract batch in two weeks.
Cold brew the coffee as explained above and then add to the bottling bucket until it tastes to what YOU LIKE!. Don't worry bout infections, just be clean and you should have no problem. Just remember to mix the coffee to your beer GENTLY so you don't introduce O2, but hard enough to get a good mix as you are tasting it.
Kaiser Ridge Brewing
Fermenting: Malahini Pale Ale
Bottled in the refe: Black IPA
Bottled in the refe: Old Glory Stout
Bottled in the refe: American Imperial Stout
Bottled in the refer: Dunkelweizen
Bottled in the refer Oktoberfest