I chose Altmer, you get 50 extra magicka points and a racial bonus I still use at level 71. Bretons have that magic resistance but if you pick a couple of perks in the Alteration tree, do a couple of quests, and pick the Lord stone the difference is irrelevant.
Plus, dont you want to be a superior born mer?
I agree. I can see why Bretons might be attractive to a lot of people, but Alteration or Enchanting can bring down their advantages quite a bit, so much so that I've made a Nord paladin who does his job better than a Breton is capable of doing.
That, and you're right about the racials. Personally, I'm too conservative with my magicka use to use Highborn so often (something I regret xD), but I've used it before and it's not going to get any less useful as time goes on. Same goes for many other powers, like the Nord, Imperial, Argonian, Orc and even the Breton's Dragonskin--that thing is
amazing against mages and dragon priests.
But, OP, I think you've gotten a lot of suggestions for race and little in the way of skill investment. At the end of the day, as important as race may be, a mage is only as good as what he knows.
I say stick with either Conjuration or Enchanting for your weapons, using either bound weapons or lining your steel with flames. I'd recommend not using Destruction, since you'll already have a means of dealing damage (unless you want Destruction for range, in which case I strongly suggest it). It'll save up a lot of perks you can use for another skill if you skip out on it. However, if you do skip it but decide to use Enchanting for your weapons, you're missing out on extra damage they could deal via the Augmented [Element] perks.
I'd suggest using Enchanting whether you use it for weapons or not, though, as conjured weapons can easily leave you with more souls than you know what to do with. Aside from profit and easy skill training, outfit your equipment with lots of boosts to your three attributes and their regeneration rates to offset the fact that you'll have to invest in all three.
As for armor, each of the three options has their advantages. Personally, it'd depend on race and RP value for me, but if you want the best-balanced stuff, I think light armor has what you're looking for.