does acar need to have power locks inorder for a keyless entry system to work?
Yes, however there are kits from the likes of jcwhitney.com that can retrofit your car with power locks and keyless entry
yes, otherwise the keyless system would not have anything to power. In other words, if the keyless system powered the manual locks then the manual locks would be powered.
You need power door locks AND the car already equipped with keyless entry for the system to work. The power door locks alone do not automatically mean keyless entry.
The car does not have to already be equiped with a reciever. You can equip a car with both the reciever for the keyless entry transmitters and power door lock actuators,both available from the aftermarket.