I'm an American living in Oslo
I am available for mentoring, particular for engineers that have ambitions to, are about to, or have made the leap to leadership positions.
I fully agree that the editor is a long term investment and I'd be VERY hesitant to switch if I was you. I am not aware of any system for easily switching your document representation to slate from draft. If I were in your shoes, I'd make a very small proof of concept with slate and only target those things which are causing you a lot of pain in draft. Only if those things turned out to be much easier in slate would I even consider the change. Avoid the rewrite if you can.
Good question! It can be quite a feat - one thing to look into is if there's any frameworks available that fit into the other tools you're already using. For example, if you use the Apollo framework for GraphQL, a lot of work has been done to make it possible to get your application to work offline. Or you could look at a library like Automerge and see if that can help you deal with those pesky conflicts. Either way, you should expect to invest some significant time. What we did at Kitemaker was to incrementally improve pieces to get ready to move to offline-first before we took the plunge and tackled the really big pieces.