A: Technically yes. Monitors are per page and there is no limit on how many you put on one site. But I would not recommend it for your case, because there is no bulk import, so 1000 pages means creating 1000 monitors by hand.

If individual pages break for their own reasons rather than the whole site going down, an error logger or server side error monitoring will tell you more than uptime checks will. Uptime monitoring earns its keep on the pages that carry the business: home page, checkout, login, a few key templates. That part is worth setting up here.