I currently have all Daedric armor and a Daedric Warhammer. All is Legendary.. I just recently got to 100 Enchanting, and would like some suggestions on the best items to use to enchant this armor/weapon to make it stronger. Help ? Thanks !

Grand soul gem obviously, and a Fortify Enchant potion - available from many Alchemists. AFAIK there is no way to learn a Fortify Enchant spell to enchant some rings/armor with Fortify Enchant, unlike alchemy and smithing which can be enchanted onto rings etc

ps AFAIK, only use 1 potion at a time, I dont' beleive they stack

Depends on what weapons you use, if you sneak a lot, if you need extra magicka, etc. I use a mix of swords and bows, so most of my items (if possible) have a 40% One-Handed and 40% Archery bonus.

Muffle and sneak fortify on Boots.
One handed/Two handed on Gauntlets, or both. Maybe pickpocket as well, I would have that on a separate ring though.
Health and Stamina regen on Armour or mix with Magica depending on your chatracters style.
Waterbreathing and Archery fortify on Helmet.
Neclace with resist fire and ice.
Ring with resist lightning and magica fortify.
Separate rings for pickpocketing, lock picking (you have to really svck at lock picking to ever need this), alchemy etc.
A good sheild with fortify blocking and magic resist are a winner too.

That will be you set for most occaisions and it is a good setup for punting your old armour onto followers when you get bored with it as well.

My standard gear is archery+ one hand on gloves, armor skill and health regen on chest, muffle and carry weight on boots (sneak is high enough)
head with archery and magic regen, (other option is water breathing)
necklace and ring is either +archery and one hand or archery or elemental resistance, naturally to go for damage first then switch to resistance later.

And yes crafting gear, at master you have smithing and alchemy on ring, amulet and gloves blacksmith apron with smithing, circlet and falmer helmet with alchemy and magic regen.

Special gear for thieving, water breathing ring.