Searched existing threads for ejector pump and didn't find my answer so I'll ask my question.

I'm installing an ejector pump in my basement for a laundry sink. It is a Liberty pre-packaged unit with a 1 1/2" threaded output.

I believe I need to install a union (for check valve maintenance/replacement i assume), then a check valve followed by a gate valve on the output line.
Is this correct?

All my DWV is PVC, should I use a PVC union, check valve, and gate valve or is it better to convert to brass for the valves and then back to PVC?

What is the preferred type of check valve - spring loaded or ball and socket?

If I use PVC for all of this are threaded or solvent weld connectors preferred?