I used to give my 8 weeks old kitten tiny pieces of medium-cooked chicken breast then gradually as he was growing up I start giving him bigger raw pieces.
Kittens should be fed more often than adult cats since their body need nutrients in order to grow.
4-5 times a day for kittens and 2 times a day for adult cats.
She is probably just jealous (cats do tend to do that), you should keep them separated at least in the next few days.
I remember when I brought home a stray kitten just for a few hours and my 5 year old cat hissed at him the whole time he was there.
He didn't sit in my lap for a whole week.