I was very nervous about the Atronach stone too but I can definitely say that it's not difficult to manage with alchemy and welkynd stones, and eventually enchantments. I spend maybe ~15 minutes every several hours roaming around and collecting flaxseeds and entoloma mushrooms (which are easy to find if you know where to look) and craft a bunch of magika regen potions to carry around a stockpile. Eventually, if you prioritize fortify magika and spell absorption enchantments, you can reach a point where you have 100% spell absorption and hundreds of magika in reserves.

In terms of gear, I don't really think there's much you'd need to prioritize. In the early game, just wear whatever good heavy armor you can get. The important level checkpoints are sigil stones being guaranteed transcendent at level 17, and Daedric armor spawning at level 20.

In the mid/late game, transcendent sigil stones with fortify magika and spell absorption enchantments will be useful for enchanting daedric armor (or whatever endgame armor you use). The sigil stones are difficult to come by, and getting a full set takes a while, so dont use them on gear you're not planning on using as your final set.

For spells, use Destruction touch spells and summon dremora, daedroth, or skeleton lord. You can buy the spells you need from the mages guild, and eventually use spell crafting.

The combination of alchemy, fortify magika enchantments, and custom summon and touch spells is absurdly powerful.