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Yes and it was mandatory for part-time employees. I worked for the county for a little over a year (resigned in Jan 2019).
Yes you will get a 1099R for it, probably in January. It will be taxable.
You can probably put it in and roll it over to a Traditional IRA Account, you have 60 days. Then it won't be taxed now until you take it out. If you do roll it over, try to replace the tax withholding with your own money so you roll over the full amount or some of it will be taxed. Ask your bank.