Yes, do sign and date it. I wouldn't make it too obnoxiously noticeable, but your beautiful work needs to be acknowledged. What a beautiful job you did. Love the bag for it too.
Very nice quilt, you should label it. Who it is for(baby), from(dil)and who made it(you) and the date or babies birthdate. Doesn't have to be a big label-I like them small.
I usually label all my quilts, even gifts if I am the one giving them. I might make up a label but not attach it and leave it to my daughter-in-law's discretion to label or not. Very nice job!