dont rent from uhaul. I have horror stories, just dont do it. They put zero maintenance in their vehicles.
Depends. Once the trucks get old enough, they basically stop maintaining them and rent them at the cheap rates until they die (generally screwing over the person who rented them). The more expensive ones tend to be pretty new and well maintained.
I had no problems with either truck that I rented from u-haul. MN to AZ, AZ to MN, no complaints except for 4-7 mpg out of the V10 ford model.