Can spayed cat still produce milk to feed a kitten?

I know this is embarrassing. But I have very little knowledge in biology so sorry for asking this silly question.

A good friend of mine just adopted a newborn found abondoned by mother in her backyard yesterday. She never had any pets and doesn't really intend to have one yet. It's just that the poor little thing was so piteous and she had no choice but to take him. She already started hand raising the kitten and I can't wait to see him tomorrow.

Now I have a 6 yr old female, spayed. I always heard that cats would often feed kittens not of their own even if they are not pregnant. I guess that it should apply to unspayed cats only. But is there the slightest chance that mine still can breast feed the newborn?

I already talked to my friend over the phone and have agreed to take in the kitten myself once the hand rasing phase is completed. (I don't have time for hand raising due to work.) So at what time would you suggest that I take over the kitten? Another issue is that my own cat is kind of mean. She doesn't like strangers and never seemed to get along well with other people's pets. Do you think this is still a problem for the newborn? I sincerely hope that she will accept him. Do you think she'll take care of him like her own child and give him the basic cat training and stuff like that?

Your suggestions are appreciated!

I am not sure about the feeding part but growing up i had a male cat that would take care of any new kittens i brought home.
He would clean protect and even teach the newbie. The cats were never alowed on the table an if he saw the kitten on the table he would chase the ktten down and meow at it.
He also would nudge them to the litter box and even showed them how to cover there mess.
He would also alow them to suckle on his stomache.
I know he never had milk but it seemed to help them adjust. He was a very special cat and i miss him dearly havng owned him for 23 years.
Sorry a little off subject. Your post made me think of him. I dont think I will ever find another cat so gentle and friendly to anything he met.
I never had to worry about him hurting anyone or anything its like he always knew what something wanted or needed. As a child if i would cry he would come running.