you may need 2 to 4 batteries this depends on how the batteries are installed,but at the bottom end it takes 24 volts to turn starter motor
There is no such engine as a Cummins 2500 Diesel.
No.
Dodge started using the 5.9L Cummins engine in the 1989 model year.
In most cases yes, they use batteries to start the engine.
You can start an 18 wheeler with 3 batteries, but if the semi sits for 2 days or more it may not start, that is why they require 4 batteries, that forth battery will help start the engine even after a week of sitting, the reason for this, is because the ECM is always pulling power from the batteries.
Probable fuel system problem. Have it looked at by a trained mechanic.
The fuel system on a 2003 is self bleeding, just start cranking the engine.
The starter needs power to crank the engine to get it running. Once the engine is running however, the alternator generates enough power to keep it running. But with no reserved power (a battery) the car cannot turn over.
When the engine is on, batteries are being recharged. If you use a lot of electric power when the engine is off, you can drain your battery to the point where it will no longer be able to start your engine, and you will need to jump-start it.
That engine needs fuel, compression and spark to start and run. You are missing one of those.
For the starting, we'd need to know the symptoms. Maybe bad batteries or a bad starter. For power on the hills, try replacing your fuel filters.
The engine needs fuel, compression and spark to run, it is missing one of those.