I've relinquished control of this issue, since I'm not working on it.

1. Is there any value in a generic instruction?

I'm not convinced of any.

2. What are the missing user stories we need to document around using the push admin ui? (eg when would a dev want multiple variants for a particular platform?)

If multiple variants for a particular platform a valid use-case (it probably is), then I'd just consider it a limitation of the current MDC (and maybe have some issue to track adding the ability to MDC), rather than documenting how to do it through the UPS admin UI. I'd rather have customers coming to us asking for support/direction on how to do a particular thing, rather than us documenting how to do things that we don't really want them to do.

3. What are the missing users stories we need to document around MSS (how to i set a version in my code to enable remote disabling?)

Maybe Wei Li or Laura Fitzgerald might be able to comment on the MSS cases, since I'm not familiar enough with it.