I have never done a tour so I can't comment on that.
Regarding restaurants, the first ones that come to mind:
• Trattoria Corrieri
• Borgo20
• OsteMagno (don't be intimidated by the owner, he is one of a kind, but one of the kindest and funniest I know) (also, this is the only place where you can still pay an espresso 0,90€. In general, this is one of the best restaurants you can find on the cheapest scale)
• Sorelle Picchi
• Trattoria del Tribunale
You have to try: cappelletti in brodo, tortelli di erbetta, tortelli di zucca, tortelli di patate, every type of salume, torta fritta/gnocco fritto.
For panini, sandwiches (which I highly recommend you try, especially the ones with pesto di cavallo if you eat meat):
• Da Walter
• Pepen