I am not sure what's the main purpose of your question..
Are you trying to build the infrastructure with DEV and PROD systems on your side? Or you already have some system set and you are trying to understand how it's done?
If the former:
There is no simple answer, it all depends on your requirements, team size, IT resources, budget.
For example: we do have an infrastructure created using 4 AWS servers. One is used a main DEV server, 3 others are used as clustered PROD system. The DEV server has 128 GB of RAM, each PROD server uses 64 GB RAM.
All other parameters (user access, streams, applications) are customizable....
Hope it answers some of your questions, but feel free to elaborate on your needs, I might be able to clarify some of your issues...
Qlik has alwways given users fully functioning tools for users to use its the licences that have restricted or enabled features.
I terms of Dev vs Production environment its how you split your reasources between the two. Qlik doesnt have a specific environment there is just functionality i.e. publishing from My Work into a stream that could be used to segregate your dev from production.