Focusing mainly on destruction and necromancy because I found that summoning atronachs makes the game too easy.

Anyway, I will be enchanting my own stuff. Can I make enchanted gear as good as the stuff you can find in the game if I don't use alchemy to buff it?

Second, will I have enough perks to fill destruction, necromancy perks, most of restoration, enchant, and enough alteration to get the magic resistance?

Yes to the first question, and second question, it depends how high you level up, but you should be able to easily.

You can perk up to 25% school reduction cost per enchantment. It's 28% or 29% with in-game fortify enchanting potions.

I've always bought training in stuff I didn't use (two-handed, etc) and grinded some things like alchemy and smithing to get the amount of perks I wanted. There is an online perk calc you can use to plan out your character (I'm sure you know).

Yes but the perk calculator doesn't tell you your level based off the skills you're going to level, it just tells you the level you need for the amount of perks you're putting in.

Here is a spreedsheet/level calculator to determine what level you'll end up at corresponding to your race and goal skill levels:

https://docs.google.com/spreadsheet/pub?key=0Ara_nWKhEraVdHg1SF9UbDJOSWtfR1liVU1YTHozN2c&output=xls

Credit goes to vtastek. (http://www.gamesas.com/user/467509-vtastek/)

If you don't want to download it, I can calculate what level you'd end up at if you tell me what skills you'd be taking to 100 and what your race is.

YEs and no. You won't be able to make anything as good as the archmage robes, or the master robes. You just can't enchant that much regen on to gear your self, or multiple enchants like on the archmage robes. You will however be able to enchant better resist gear, and better fortify school gear, with the ability of putting two enchants at 100 skill. Still, at level 45 with 100 alchemy and enchant, I still use my archmage robes, but ring, necklace and circlet are self made.

I didn't bother with perking the skill levels (adept - master) for several schools because of the fortify school enchantments available. I have master robes and the archmage's robe but I don't use them because my enchanted items are more useful. I enchanted a college robe with fortify destruction and alteration. That with a similarly enchanted ring, necklace, and hat (or circlet) is good enough that magicka restoration and spell cost doesn't matter. For those times I use an out of fortified school, I use fortify and restore magicka potions to boost back up. I also have some miners clothes dual enchanted with fortify illusion and alteration.