Considering the efforts RD (Don Davis) puts into providing meals to SOS participants, this tread should not go into direction of "supplemental caloric intake." You will be treated to a pre-race dinner on an evening before the race (catered by a good local restaurant), lighter meal at the finish line (soup and chili, fruits, etc.), and huge meal at the awards (catered by the Mohonk Mountain House). Sadly, over the recent years Don Davis succumbed to the whining of some of the more fresh to triathlon athletes, and began to provide nutrition and hydration ON the race course. Shocking! SOS definitely lost some of its ruggedness and "survival" flavor when aid station volunteers meet you miles away from civilization with "What flavor of the gel would you like?" or "What type of fruit would you like?"
Over the years, and independently of the weather, most participants tend to wear standard tri racing apparel once off the bikes. Tri-shorts or swim suit, maybe singlet or tri-top, maybe one-piece. Some use wetsuits (for speed or comfort) on the swims, some create elaborate shoe-carrying designs for the lakes, some stay minimalistic.
Water temperatures varied over the years, and can change dramatically in just 24-48 hours prior to the event (due to rains and rapid temperature changes late in the summer). Only the first lake (due to the swim distance) can became a challenge due to its water temperature. It can get pretty challenging for lower body fat athletes (in the late 80's, one year had dozens of swimmers periodically getting out of the lake to the shore to warm up and to release cramping). But usually, water temperature does not affect most swimmers until the last 5-10 minutes.
As for shoes - too many options had been used already to suggest anything new. From wearing them, to storing them under the apparel, to waterproof bags, to rafts... all methods had their proponents.
Race can accommodate only a very limited numbers of participants, so if you are serious, fill out your application right now. You also need to qualify (see race website).