Campanile Paris XVII Boulevard Berthier

you have good general advise so far, the local five cent worth is this

It all depends on the status of the restaurant, i have eaten late in many restos that says close by 11Pm and I stay eating until 1AM ! Ask the people in the VT Paris get together,the resto i took them too, and see my paris pages.

Your seating 12-2 again it depends on the resto if you arrive by 1H30 some restos will tell you wont take anymore clients if they close the restaurant by 2PM so they can go home and rest and reopen later for dinner usually 18-19H.This is usually in the provences, like Honfleur, for example. Paris is really gear towards tourists so this policy is more flexible. It really makes sense to make reservations always.

Some restos dont have the habits of taken reservations ,these are the more informal ones, inexpensive or whatever word you can use; the moderate upper upscale,restos all are suggested strongly to do reservations.

You can sightsee around the time you make the reservation, planning is the word.In your case, I strongly suggest to make your reservation by 1H30 ,and they will tell you if ok or not.

Now once you are in, yes ,you can take as much as time as needed. YOu can change items in the menu in most, (I know the problem my kids do it all the time and its ok) Again, its all depends on the status of the restaurant;but in tourist oriented ones, this is no problem ,especially in Paris.
the bill for paying, you ask for it when ready, some restaurants not the upper ones, allowed you to get up and pay at the cashier up front. YOu wont be penalise by doing this in any.

There is a myth to French restaurants but they are as the status of them, and the area where they are, Paris is an exception, tourists are king. I know in my job I do consulting work in finance to deluxe hotels and restos in France, and used to work for a major international deluxe chain with historical monuments in some restos that for ethics cannot mention.

Be yourself, get your reservation, plan your sightseeing,take your time in eating, ask for changes if you think is reasonable, and ask for the bill l'addition svp ::) bon appétit !