One thing I would certainly suggest would be a redundant air source, in the event that your primary regulator should freeze up & free flow, to get you safely back to the surface. Yes, it is possible to breathe a free flowing regulator to the surface, but it will deplete you cylinder very quickly. I've done it from 95 ft. Some regulators are better suited for cold water than others. I use a high performance regulator, which is not really the best for that application, but I have also learned how to make it work for me on a dive. Also gloves & a hood may be necessary. Be aware, that unless you are used to gloves, thick ones will decrease your finger dexterity considerably. Hoods,.... God I hate hoods. A necessary evil in my book. Most people feel quite confined in them, some even claustrophobic. Make sure it doesn't get under your mask skirt, or you'll be flooding like crazy.