1. Think of it like updating a JavaScript API without breaking existing callers. The rules are essentially the over RPC as they would be for local calls. So, you can add new methods and new optional arguments, etc.

2. After losing the connection, you'll have to reconnect and reconstruct the objects from scratch. The way I've structured this in an actual React app is, I pass the main RPC stub as an argument to the top-level component. It calls methods to get sub-objects and passes them down to various child components. When the connection is lost, I recreate it, and then pass the new stub into the top-level component, causing it to "rerender" just like any other state change. All the children will fetch the sub-objects they need again.

If you have an object that represents some sort of subscription with a callback, you'll need to design the API so that when initiating the subscription, the caller can specify the last message they saw on the subscription, so that it can pick up where they left off without missing anything.

Hmm, I suppose we'll need to do a blog post of design patterns at some point...

A blog post of design patterns would be really great. Again - amazing work!