This works out well you usually don't have to pay them in advance. Auto-rickshaws are considerably faster and could be twice as expensive, too. The day-long contract will work with them, as well. But, an advance payment may be necessary. Needless to say, the ride would be very pleasant if you offer them a little more than they demand.
Bargaining is the keyword.
There are hundreds of restaurants and snack shops throughout the city. Most of them would fail every test of hygiene, according to western standards. The megamap of Kanchipuram in this site has a few places marked for restaurants. Those are the places where you will find the most hygienic restaurants in the city. A few of them have been listed in the Directory page.