Yes, it's true that no races with two mental bonuses and a physical penalty exist. Doesn't make sense to me, since a physical penalty cleanly fits two bonuses to mental stats, and vice versa. But I don't really see the issue with trying something new. Experimentation with new things can make things more interesting, especially when it's with a player character. Yes, it's a little strange, but it's fair, to be certain.
In the Dungeon Master's Guide, page 173, rules for balancing ability scores are presented. A bonus to Constitution carries less weight than a penalty, though; a bonus can be balanced out with a penalty to any stat (but Strength would be a significant loss, as Strength is considered to be the most powerful ability in terms of balancing stats), but a penalty would be too much for just a bonus in Wisdom OR Charisma to balance out; indeed, a bonus in Strength or Dexterity would be required. Strength and Dexterity bonuses are balanced by a penalty in two mental stats, meaning that it can be assumed that a penalty in Constitution is about equal to two mental ability bonuses. As such, it is more or less balanced, and I don't think that any of the racial features really push it out of the fair category. A penalty to Constitution with a bonus only to one mental stat would be unbalanced, on the side of low stats.
As for the resistances, would you have any particular problem with the distributed resistances, or is there a specific reason you suggest a large bonus to one? Not challenging a decision, it seems more than fair (and allows for customization on a racial level - nice, seems very cool), but I just want to know.
Oh, and as for taking a progression level later on to become a full Aasimar - not really an option. I plan on going into Paladin, which doesn't really allow multiclassing.