Is there canoe/kayak rental?

Yes

Yes, at head quarters, it's called Nemasket Kayak Center, you'll need to call ahead now I think http://www.nemasketkayak.com/nkc-hours-of-operation-wareham-ma.html#Xxr_v34_PlymouthHoursOfOperation

Yes at headquarters where you check in..

I don't believe there is. Check out the Plymouth area for rentals. They may offer a delivery and a pick up service. If you need that option.