Multiple Sclerosis and Medicare

Well, I received my medicare card in the mail today. I am excited that I may not be paying Regence anymore, but wary about what my coverage and cost may be with Medicare.  Anyone out there know about Medicare as it pertains to MS?  I will be looking into blogs and message boards for information, as well as emailing a few folks.  I need to know if it is going to cover things like MRIs and my Rebif injections.  I also have several muscle relaxants and medications for spasms, as well as something to keep me basically awake and somewhat focused during the day.  If anyone has any information about Medicare and MS, please respond!  Meanwhile, I will look and see what I can find, then share it here.