From what I've read the major receptor subtypes involved in the antidepressant effects of SSRIs are:
Please cite journal articles to back up your claims, I don't want any piece of information to be unverifiable.
You're right, those are all important! There are several good reviews on the mechanism of action antidepressants. I like Molecular Pharmacology, by Nestler, or even Principles of Neural Science, by Kandel. I think a textbook is going to be your best bet, in terms of getting up to speed here, as this is largely an already-researched issue, but here are some good review articles as well:
If you have a more specific question, let me know!