What to expect with a newly adopted 4yo?

My wife and I just adopted a 4yo French Bulldog and we are first time dog owners. She came from a rural town and now lives with us downtown in a good sized city. Since coming home with us she has not eaten or pooped. Also, she is potty trained but refuses to go to the bathroom while on walks. Instead she will pee on the carpet almost immediately after getting back from our walk. 1) Is it normal for a dog not eat for 3-4 days? 2) Should I do something different to get her to pee outside on our walks? 3) Do you have any tips or notes about recently adopted dogs?

Thank you!