Nobody can tell you what boot will be the most comfortable for you. Luckily there are plenty of stores that carry different brands for you to try on with the socks that you intend to use. Slightly too large boots are vastly better than slightly too small boots.

As for boot construction, I like either Vibram deep lug soles or airbob soles that are stiched to the upper for mountain hunting. The airbob soles do not hold as much mud and still have very good traction, the deep lug soles fill up with mud but have great traction on rocks and loose scree slopes. Some guys like the molded soles instead of the stiched version, but most fellows that hunt steep rocky ground want a boot that supports the ankle well and has good traction (not "duck" soles). I like the "lace to toe" boots best for the mountains but other guys like boots better that only lace to the middle of the foot.

The best advice that I have ever been given for cold feet is to put on a warm hat. This is not a joke. You lose so much heat from your head that your body compensates by robbing it from other parts of your body, starting with the extremities.