it is OK to drive the car to the US. The catch is that some of the car rental companies have a limited mileage/day. So be sure to ask about this when you rent.
some of the issues you want to be clear about:
the daily rate, insurance (collision, damage, liability), road side assistance, and if there is any mileage limit (see above).
As to the insurance, some of the credit cards can cover you the collision, damage insurance if you use the credit car to rent the car (most of the Platinum cards and American express card covers your insurance, so you do not have to buy it from the rental company). Liability is up to you, if you have an auto insurance, that insurance will cover your liability. Have a nice trip.