SharePoint Online solution pack for branding and provisioning was initially released back in last March with 5 specific chapters. This package has been now refreshed to included two additional chapters with specific additional guidance on FTC to app model transition, metadata and publishing topics. This is material has been reviewed and approved by the Office365 product group and is written by the technical writers in the MSDN based on the work done in the Office AMS CodePlex project.
Here’s direct links to the solution pack materials
If you have any feedback or suggestion on the Solution Pack, please the Office SP Dev User Voice as the channel to get the message to right persons.
Material is divided currently to seven modules which each concentrate on the different topics around app model. Here’s short description for each of the models.