Build a Cloud Operating Model - Best practices of running Office365 services on a Single Tenant

And what work have you done to date to research operating models for Office 365 to identify the issues that you think are most important and those that you need most help with?

I don't want to be rude (really!) but what you're doing is asking other people to figure out best practice for you. That's an impossible task because best practice in the eye of one person is rubbish in the opinion of another. In effect, best practice means what is most effective for your business. And you know your business best of anyone, so you should do the basic research and then ask some precise and pertinent questions. There is more than enough written and published on the topic.