Living in a tropical environment (Darwin, Australia), i do almost all my large urethane pouring from the fridge. It slows the cure time waaaay down and should down on moisture contamination. If i'm doing multiple copies i'll pour the next batch of both parts into jugs straight after i've poured the previous mould, that way i can demould and have a quick clean up and my next resin is cold and ready to go. You're other option is just keeping it in the fridge (best to have a small bar fridge in your workshop as it's also handy for knockoff beers!)
As for bubbles, now that it's cold and kicking slow pour slow and thin, that should get most out.