That sounds odd! The shopping cart might be part of a new feature or an experimental add-on that got installed. You could check your extensions or add-ons in Firefox to see if anything looks unfamiliar, or try updating the app to the latest version. If it persists, a quick reset of Firefox settings usually clears out anything extra without affecting bookmarks and passwords.

This is the indicator of your profile. It has been added when you've created an additional profile. You can change this indicator in the Profile Manager.