I will be in Paris for a few days, including on Sunday. What can I expect in terms of public transport, shops, restaurants, etc? Is anything open, or am I meant to spend the days at home?
Many bakeries will definitely be open. Supermarkets in France are increasingly open on Sunday morning, even outside Paris. Some restaurants might be closed on Sunday evening but you should easily find alternatives.
Specialised shops might open, especially in the period leading up to Christmas but you cannot rely on all of them being open. In most places, they are only allowed to open on a limited number of Sundays but there are seven areas in Paris where shops are allowed to open every Sunday.
Museums and attractions will be open on Sunday, most of them close on Monday (many museums in Paris) or Tuesday (Le Louvres and a handful of other Parisian museums, national museums outside Paris).