with the temperature being displayed on the screen as a numerical value?
Two parts to this:
- As far as displaying a temperature goes, I've been asking myself this sort of thing for a day or so now. My feeling is that most would find a oCelcius readout immersion-breaking, since temperature measurement isn't really a thing in Tamriel. I'd be quicker to display descriptive things like "warm", "cool", "freezing". That being said, if this is something people want, I can make it an option.
- As far as a permanent user-interface element, this is an area I have zero expertise. My plan was to provide helpful (non-spammy) text notifications in the upper-left corner when things change, as well as give you some method in the inventory screen to invoke a menu to tell you the current situation.
For number 2, I really, really need to talk to someone who knows Scaleform UI and can tell me if adding such a UI element would play nicely with people's SkyUI installation (which I personally use).
Will the flame cloak spell, and indeed, taking fire damage, replenish EP?
I'd like to compartmentalize combat mechanics away from survival mechanics. To wit; the flames in your hands with a Flame spell readied don't burn your hands, so neither should they keep you toasty warm. Same for damage, it won't affect EP loss or gain.
However, frost resistance does play in to your EP preservation. I did this because a) it makes sense, and

it means Nords can stand the cold better than others automatically, and I don't have to edit their race. I was about to agree to Frost Shield giving you some sort of bonus, but I see now that there's no elemental resistance spells in Alteration, which is...buh? http://www.uesp.net/wiki/Morrowind:Frost_Shield, http://www.uesp.net/wiki/Oblivion:Frost_Shield.
Summary: aetherial magicks are all wiggidy-woogidy and won't mess up your vibe.