Hey Jo Shmoe,
The Add F doesn't like cold weather and makes the mix really cloudy, but I've found it is not noticeable once you get it on the board. One little trick is to put the ADD F can in a small bucket of warm water for a bit before you add it (specifically in colder weather).
Mark - as for the Football Patches -- I think Jeff is probably right that they are not really needed, but I like to put them on my boards just for that extra strength just in case. Would rather spend 2 mins putting them on than worry about someone bringing a board back with a ripped out fin box. Sometimes on Lake Austin after a good rain, I've had the pleasure of running over small logs or branches while surfing. So far, haven't ripped a box out yet.