Yes, you need to have 240V
Yes, you need to have 240V hooked up to the car to see the 2.5 hour charging times. For reference, 120V * 15 A is 1.8kW, which means you would not be maxing out the charging speed of even the 3.3kW charger. To hit 3.3kW, divide 3.3kW by 240V to see 13.75A, which is how much current you would need to be drawing to max out that charger and hit the 4.5 hour charge time. To max out the 6.6kW one, 6.6kW/240V = 27.5A, which would require wiring up something like a NEMA 14-30 outlet. NEMA 14-50 is what you'd typically find at a campground, so it would probably make sense to wire that in, and then have that plug handy anytime you go camping at an RV park.
Hope that answers your questions.