ejector pump install

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?

Thanks,

Joel

I use Zoeller check valves with the rubber boot/SS banded clamps. Has the flap inside of it. I've never needed a gate valve or union. I have seen them installed on some applications, does make it easier to switch out a pump easier but most times the valves are jammed open, the unions will break down only if someone used grease or sealant to allow the union to unscrew. Most times those unions will "glue" themselves together because the O-ring inserts will flatten, allowing the connection to leak. I just replaced a O-ring on a water softener for the same exact reason; rubber was flattened from the years of being compressed.