Celebrating Nabi (sallallahu alaihi wasallam)'s birthday

Q: Someone sent me a link and said that Nabi (sallallahu alaihi wasallam) celebrated his birthday because of what is stated in the link. Could you please calrify and tell us a way to explain to them why we cant celebrate Rabi ul awwal?

Did Nabi (sallallahu alaihi wasallam) fast on Mondays due to the fact that he (sallalallhu alaihi wasallam) was born on a Monday?

Woman covering her hair in the house

Q: I've come across on Muftionline that Mufti Saheb had mentioned regarding a person covering their hair during eating is something that Mufti Saheb had not come across. Is there any virtue that a woman covers her hair during eating? Anything about drawing barakah? There are quite a lot of people who say to cover the hair whilst eating. Another thing, like the above, is there any virtue in a woman covering her hair whilst sleeping?