We're looking at having individual stores for different organizations to place orders on. Each microsite would have it's own content. Is this possible to create under one "site" or account or would these each need to be individual websites/accounts?
Did you get answer to this question. I am looking for the same.
You're basically looking to create a marketplace - there are apps which can help with that though it's not the intended use of Shopify, which is really designed as a 'one merchant one store' platform.