You do to a point, bit its not super restrictive. Certain kinds of seafood can have a lot of mercury and toxins that can be passes on through breast milk and effect brain development. Not all though, so just look up which ones are safe and pig out as much as you want :) Coffee is fine, it won't hurt them....but you will probably pay later with a cranky fussy baby who wont sleep. Caffeine has a longer half life then alcohol so even if you pump and dump they will still get some...its up to you!
Yeah you do.. from what I hear! Haha I think pump and dump method works with coffee as it does alcohol though as for seafood I have no clue ;) goodluck