Greg, as far as heat packs I just go to like a sporting good store and buy them there they are cheap and last approx 8 hours. with the weather nice you should be allright. I get my boxes from my wifes work. I triple bag mine and then wrap in news paper and I scored some 1/8 inch foam form an uphoulstrey shop and insulate the stuff in that and works pretty good.
I either go through DHL or Fed Ex for shipping