i'm actually considering throw-away shoes to wear to the start - if it's raining, that's what i'll do. i'll keep my race shoes in a bag until just before the gun. i've got several old yard-work pairs around the house.
i've also seen guys walk around befofe the start with plastic bags tied around their shoes, but it can get really slippery.
wear the lightest socks you can, since they hold a lot of water.
hard to predict the conditions. but, if it's low 40's and windy and wet - i'll wear more than a singlet. if it's gonna be any warmer, i'll start with a throw-away shirt on top and discard it when i get warm
i'll definitely have disposable gloves. whether the hat is disposable or a tech-fiber running hat depends on the conditions Sunday morning.
FWIW we've got a couple of pace groups - 2:55 and 2:57ish starting in the competitive corral. meeting place and time can be found on threads on RT and RW if you're interested