You get 18 months before you lose your seniority. When you do come back there has to be a opening in your job class. If not and you keep in touch with SCM he will put you on the dock until he opens a slot for you. It is very rare that someone comes back after 18 months. As for paying for insurance, you pay for cobra or you can pay for Medicare from SS. Cobra is about $270 more a month than Medicare. I choose to pay for Cobra because I know FedEx insurance pays for all my treatments but not to sure about Medicare.