Q: Is the solenoid and starter one unit or separate.

Most if not all starters on the market will include the starter solenoid with the replacement starter for this car. You may be able to purchase the parts separate but it is not common practice since it adds labor to the job of replacing the starter. If you are having a problem where the starter is just clicking but does not crank then your solenoid is operating but may not be sending power to the starter motor or the starter motor is just not turning. I would recommend having a mechanic like a mobile mechanic from YourMechanic come to you and diagnose the no crank condition. You may need a starter replacement or have another issue like bad battery or cables and a mechanic can check entire system to make sure entire system is fixed correctly.