There are no more "types" in indices...they have been removed see here
Think of a mapping as the schema of an individual table in an RDBMS.
To add a to the confusion 
That table could have many fields that are sparsely populated and a field that indicated a type if you like.
discuss Is the index name.
If the schema of your data is wildly different, you would probably want to put it in two different indices / mappings.
If they're close / similar and you just want to indicate that there is some field that tells you which type it is so you could sort or filter that's fine too.
What has been removed is setting
_type to anything other than _doc
With respect to development on prod and production to me, it's like any other datastore ... You develop in development, tested out and staging or non-prod and then you promote thank you production.
Let us know when you have some questions on queries. Open a new thread.
Glad you're moving forward