Is Serana's Health,Stamina,and Magicka recovery affected by sunlight in the same way the pc is when a vampire ?

Yes.

And if she is cured ?

(I have read that she still uses vampiric powers after being cured)

Dunno. I didn't joined the Dawnguard in any of my playthroughs (and probably never will). Regardless, if she still behaves like a vampire, she might as well stay as one.

She is still essential and infects the Player Character with friendly fire with Her Drain Life, ressurects dead creatures, but She is not a Vampire.

I don't mind her using vampiric drain after being cured...but I would like to cure her of weakness to sunlight...but if she is bugged and even after being cured still has the weakness to sunlight then I would keep her as a vampire,the glowing eyes look great on her.

If You are not on a PC and do not have access to a Mod to clean the whites of Her Eyes, I agree that allowing Her to remain as a Vampire is a better choice.

So can a pc user confirm that curing her removes the weakness to sunlight...or if she is bugged.

It's not a big deal. The effects it has on npcs is negligible to be frank. NPCs have a much higher magic recovery to begin with and her spells don't use up that much.