Lived there for two years and November is cold, so take some warm clothes and good comfortable walking shoes.
On arrival at CDG get the free shuttle to the train station to transfer onto the RER into the heart of the city. Air France bus can take hours depending on the traffic on the Peripherique.
Tell your missus not to carry a handbag, best to put your cash in the front pocket of your jeans. I personally never had any problems. Use the RER if possible as its super quick.
Louvre used to be half price on a Sunday but you could spend 5 days in there easily. Montmarte is a must see, if you go on a clear day pay the extra to go up on the roof of the Sacre Couer and visit the crypt.
It's amazing and you'll love it.
If you are on a budget most cafes do fixed price menus for the workers at lunchtime and you can get a two course meal very reasonably, albeit a limited menu, but try some local fayre.
If you are looking for food to take back to your hotel room, each arrondissement has a market where again the food is fresh and cheap, The French avoid supermarkets and buy fresh every day.
If going out to restaurants/cafes in the evening to eat look for places packed with French folk and avoid the tourist traps