Medicare Coverage with a working spouse

Hi everyone!

I am hoping someone can point me to some links that will help my DH and I make the best decision about his Medicare.

My DH is 64 (will be 65 in February 2011), is retired and collecting social security. I am only 47, still working full time, and covering both of us on my medical insurance.

From what I understand, DH still needs to apply for Medicare Part A before his 65th birthday, even though he is covered by my insurance. My biggest questions are about what other medicare parts he needs to sign up for. Can he delay signing up for the other parts? Are there any penalties to delaying?

If I should die before him, I assume he would immediately be able to sign up for the other parts?

Thanks for your help!
Jeannie