Can i put magicka regen enchant to my whole set? boots head, cape, gloves? and if i can, it will really work in addition to the points? like 50% from each piece or i will have just 50% magicka regen at all?

Headgear, chestpieces, and rings only, according to the http://www.uesp.net/wiki/Skyrim:Regenerate_Magicka. Much easier to put magicka cost reduction enchantments on items: you won't have to regenerate magicka you don't use.

The enchantments stack onto each other. so if u hadan enchantment on Head, body, and ring that +50% each, it would be +150%