1. The number of PV panels should be enlarge if you need to install the battery in the system; The extra PV panels are required to charge the batteries while the pump working.
The cheapest option is to try and fill an elevated header tank or if you have no elevation locate the tank near a utility power supply so you can pump water from the tank using a mains powered pump.
You must use deep cycle batteries not car batteries. Deep cycle batteries are designed to take much lower continual discharges than regular car batteries. Deep cycle batteries
normally have an "amp hour" rating shown as AH, for instance 100AH