Nathan just posted a gist with some nice code examples for managing a file storage location and permissions on a file object in c5 v8. We are working on a project where we want to store documents in a secured location (outside of the web root) and programatically set permissions on the file objects to prevent unauthorized access. This is doing the job nicely!
Wireframing is both creative and technical - here are some good guidelines for capturing everything you need in your wireframes. https://www.smashingmagazine.com/2016/11/wireframe-perfectionist-guide/
Loads of bugfixes and goodness. Getting close to production ready - we've built a few test sites and have our addons ported to the new platform and can't wait to get going on new projects with the shiny new c5.