cooking

Q: Why is it said in Islam that women are not supposed to cook for their husbands?

Q: I agreed with someone more than once that I will cook something for him as he helped me study. Now I don't really talk to boys. Will it be right for me to cook for him as I gave him my word and it is really important in our religion or should I avoid it?

Q: Is it permissible to watch cooking video clips on youtube where faces are not shown?