Can I store additional metadata for resources within meta?
You can, and we encourage it. We recommend that you avoid changing the values of the request statuses directly (use the built-in Action types to do this), but feel free to store anything else in there that you want.
You can use the UPDATE_RESOURCES action type to change the metadata of resources.
If you'd like to update metadata alongside a request, then you can write a plugin for that.
A future version of Redux Resource will support this without a plugin.
Can I store additional properties on each state slice?
Yes, you can. The only requirement is that you don't change the structure of the state that you start out with: make sure that resources, meta, lists, and requests remain Objects. If you stick with that you shouldn't run into any issues.
As a convention, we recommend only storing data relevant to the resource in the slice. Use another slice for other information.
Can I store more than one resource per state slice?