Vital Records are available at the Library of Michigan, here's a link to some of that information. Most of the information posted here (or any any genealogy site) gives details on how to obtain the information on these records. Purchasing an official copy of a vital records is different. Here's where you can find that. Oakland County does not have much of a way to get information without ordering the actual certificate. Here's their site, but notice that you can only order birth records through the online system for persons born after 1935. If your dead people were born before that you'll need to print out this form and mail it in with the $15 fee and a copy of your drivers license. Here's the mail order death certificate copy and here's one for the marriage, neither of these need copies of your driver's license and they are also $15 each. They don't get into it much on the website but the data you seek must be post-1867. I am having a hard time surfing the laws of the state but from what I can gather 1867 was the year. What confuses me is that some counties seem to follow other guidelines, or at least they used to. Lapeer says here that they have marriage information dating from 1833. The Jackson Co Genealogical Society says here that they're library has sources records of all kinds from as early as 1830. Here's a rootsweb conversation about vital records.
I'm exhausted! Maybe I'll try and tackle Macomb later.