yep who knows, maybe during that operation Tony had at the end, the surgeons did more than just removing his arc reactor, maybe they put some extremis inside him too?

and BTW since Iron Man 2 all of the armor had its own arc reactor right? They weren't powered by the one on Tony's chest.

It's because all the suits were kept underground, the entrance were blocked by the debris of Tony's destroyed mansion. Then they showed that scene where the debris were cleared and the entrance could now be opened and the suits can finally be summoned.

Damage suit wont be 100%? U mean the mk42?

He's like a combination of those 2 characters.
It's not like this is the first time they ever did that anyway, in Iron Man 2 the Whiplash that appeared in the film had elements of Crimson Dynamo.
Just like how the Adrich Killian in this film has elements of the Mandarin, those dragon tattoos, crushing and karate chopping iron man suits in half with his own bare hands, that's exactly how I'd imagine The Mandarin would be.

IMO Guy Pearce was more the Mandarin than Killian.