Basically I'm wondering if can do without the atronach perk as I've heard it's heavily bugged when using conjuration which is a problem for me because I plan to use bound weapons a lot.

I'm not really bothered about my character absorbing magic but I do want him to be protected from it as much as possible. I know atronach absorbs 30% of any magic that hits you but does this mean that spells will only do 70% damage to you and the rest of the damage is ignored i.e if someone hits you with a spell that would do 100 damage without the perk, would it do only 70 with the perk or is this not how it works and would it do 100 damage always with the only effect being that it fills up your magicka?

Also if it does protect does it stack with magic resistance (x3) meaning an overall magic protection of 60%?

Atronach perk gives 30%, Stone does 50%.

I believe the resistance and absorption work together. Its going fine with my Bronze Sentinel Build.

Cool sounds good then I'll go with it

Are you on PC? The Unofficial Skyrim Patch fixes the absorb problem with summons.

The spell absorption bug does not affect bound weapons.

But absorption differs from resistance in that you have X% chance to completely absorb the spell with absorption, whereas with resistance, you will always reduce magic damage by X%