Any Metro HQ employees here?

I have recently been given an offer from Metro to work at HQ as a SDSA for a full time position. I couldn't find much information online anywhere and I'm wondering if there's a probation period? Is employment at-will and do layoffs happen at Metro? One reason why I am considering the public sector is because I've been laid off 3 times within the past 3 years. I want job security and stability. It's caused me to lose confidence in myself and my ability to do any job. I've got 7 years of experience working.

How is the workload at Metro? I've seen reviews stating that many are coasting, and others where they do the jobs of 2-3 people. I certainly wouldn't want to be taken advantage of like that.