As long as your husband's employer coverage is considered creditable coverage, you can delay enrolling into Medicare, including Part D. One to two months prior to coming off of his coverage, you should have a conversation with a broker on how to enroll, when, and what your options are. Keep in mind, for Part B and Part D, you will need to have proof that you had creditable coverage since you were 65.
Yes, since your husband's employer plan covers 20+ employees, it counts as creditable coverage for both Medicare and Part D. So you can delay enrolling in Part A, Part B, and Part D without a late enrollment penalty as long as that coverage stays in place. Once the employer coverage ends, you'll get an 8-month Special Enrollment Period to sign up for Part A and B, and a separate 2-month window to enroll in a Part D or Medicare Advantage plan with drug coverage
Yes, you can safely delay your Medicare enrollment, including Part D, without facing any late enrollment penalties. When his employment ends/health coverage ends, you will trigger a Special Enrollment Period to sign up for Medicare and any supplementary plans penalty-free.
Yes, you can delay as long as you stay on his plan and his is employed. You should compare your cost options and see if it would be cheaper to go on Medicare.