Big old WIP that won’t be entirely out-of-progress until there’s been a thorough sensitivity read of whatever I first come up with. 
Absolutely!
“How much they trust that they can live with the post-Hegemonic regime you’d put in place.” For many of them, “live with” does mean “dominate,” or at least “continue to wield power disproportionate to their numbers.” Others would just be more like, “seems like under this ${woman}'s rule we’d get to live free from Karagond oppression and Kryptasts while still getting to keep most of our land and wealth, as well as our lives. Sounds good.” Most aristos don’t have huge estates or vast amounts of property anyway; your popularity with the “average aristo” will be different from how the magnates of the realm see you.
I’ve never gone anything close to “full Dægbeorht” – the old names are just a little more Germanic.
An excellent question whose answer will await another day.
She’s 38, so late middle-aged? I guess all the teenagers reading this will think “yes” and folk my age will think “no way.” I like your mental images, none of which are inconsistent with my vision, except that I think I described Jev a couple places as having long strands of yellow hair.
Finally, one of the things I’ve been doing this month in between writing is scouring back over the 13,000-ish posts in past XoR threads to make sure my current plans for the G5 endgame will catch most of what readers have speculated about over the years. (Some of you might already have guessed this as my likes belatedly pop up on your 7-year-old posts. I was stingier as a young writer.)
And I wanted to very belatedly confirm that @cascat07’s nerd-fu is strong:
Your calculations all check out, with pretty impressive accuracy given that you were working from my handwavy “Greenland-like” comments and a large-scale map (which I tweaked a year ago to avoid Mercator-esque distortions in the original projection). Total area of the Hegemony is 7,561,350 km2. That’s Shayard at 2,167,630, Erezza 2,057,598, Wiendrj 1,545,950, Nyryal 1,281,873, and Karagon 598,299. Nice work.