Would it be possible to rent a canoe through the week, i.e. Monday through Thurs or Fri? If so, what are the canoe model options and prices?

Yes they rent for up to 5 days for canoes and can deliver and pick up for a fee.

Can their paddle boat seat 4 person. Is it the kind 2 person sit forward with foot paddles, the other two person seat backward?

I don't think so but renting them for 4 hours is actually surprisingly cheap. We've rented a paddle boat for like $50 for 4 hours.