Retirees - medicare eligible vs. non eligible

Does anyone track the difference between retirees who are eligible for medicare and those who are not eligible for medicare?   How are you tracking them?   We are self-funded and the retiree enrollments are in EBS so we should be able to generate a 1095-c for them, correct?                                  

For COBRA participants due to termination that are handled outside of EBS, how are you generating the 1095-b if the vendor is not providing the form but will provide a spreadsheet?

Does anyone have clear definitions for Assessment Periods and Stability Periods?