First long swim, last minute questions

I'm entered in my first long swim, the Potomac 7.5 mile race, on Saturday and have some last minute questions. Goal is to finish (I don't care if I'm last or if I set a new record for slowest finish; just want to get from one side of the river to the other). I've never done a swim long enough to require a taper. When should I do my last long swim, or should I do only enough short swims and cross training to prevent lactic acid buildup? (I did 5 miles on Saturday, two on Sunday, took yesterday off). Should I take the two days before the swim off completely or do some easy swims/ cross training? How often to stop for hydrating and feeding? I know some stop every half hour to hydrate and every hour to feed, but that seems like a bit much. Would every hour for both hydrating and feeding be OK, or is there a psychological benefit in stopping every half hour? And is it better to stop more frequently just in case? And what have you used for feeding? I've tried gel packs and Power Bars and Larabars at different times and they all seem to work OK. Would bringing some sort of hot or warm drink help with preventing hypothermia? And any advice on what to eat right before the swim? My plan is to start out very slow and easy, about a 45 minute mile pace (don't laugh); I can pick up speed later if I want to and can. (I did a two mile race last Sept. at about a 38 minute pace). I'll probably do some breastroke to spare my shoulder and save energy, and going at a slow pace will save me for any current/ chop/ waves at the end. Fortunately there are no time limits on this race! I appreciate any advice any of you have. Thanks! Sandra