Most of the better restaurants are closed Saturday afternoon until sundown for the Sabbath.
You say cuisine is not important, but are you more of a meat eater or dairy? And what's the price range?

Cafe Rimon is a place you can never go wrong with. There are 2 locations, one just off Ben Yehuda Street, in the center of the city. They have both a meat and a dairy restaurant there (Perhaps someone can correct me: last time I was there, the meat place was still closed for renovations, but has it opened since?)
The other location is only dairy, and is located in Mamilla Mall.

On Emek Refaim, there are a bunch of places, many of which are good. Two of my favorites are Joy (meat) and Luciano (dairy). If you can give me more information of where in Jerusalem you'll be, price you're looking for... I can give you better results (hopefully). Enjoy!

As for tours, it takes years to tour Jerusalem! There are tours that are comprehensive, informative, and enjoyable, by the Old City that last only a couple of hours. Let me know if that interests you, and I can PM you some more detailed info.