the heads-up display was totally worthless (at 6 foot tall, I couldn't adjust it upward enough to see the HUD without slouching or lowering my seat);
I hate to say I can't offer anything helpful regarding cold feet. I had that problem big time in my 2005 Mazda 6 with my feet always freezing. I haven't noticed the issue with my MZ3 sGT hatch though. Though I will say I'm not in as cold temperatures as you are.
I found your comment interesting though about the HUD - you sure you didn't adjust it correctly in the infotainment? There is settings in there for its height. I only mention it cause I'm 6ft as well and have no problem getting the HUD adjusted to a useful spot for me. In fact, I absolutely LOVE the HUD.