I think one cemetery is enough--this is short walk from hotel, hosts the graves of Bartholdi, Dreyfus, Du Maupassant,Citroen....I'm not sure about doing the catacombs, since I have a bit of "underground phobia". Tell me more of your experience there, please.
The food street should be Rue de Montparnasse and markets are Blvd Raspail. I plan to take comfy shoes, muscle cream and hot baths after a long day...