How to deal with new product version?

[sopuli]

Dear Support Team,

As my project (webhelp output for our software product) is progressing and actually publishable, I have been asked how I will deal with our next software version.
At the moment, I upload my webhelp output folder to our web server, and that's it.

How will this work with 2 (or more) different versions?

My understanding so far:
1 - I would only need to create another ditamap for the new version that contains all unchanged topics plus either the amended topics (with versioning elements) and the new version's own topics.
2 - I would publish 2 ditamaps and end up with 2 webhelp output folders.
3 - In my transformations for both ditamaps, I would need to add a "version switch" for the website header.
4 - On our web server, I would need an additional target folder for the new version.

Are these assumptions correct?
Could you point me in the right direction for more information about version information in topics and version selectors for the webhelp output, please (tutorial, help files)?

Thank you so much in advance!
Best wishes
Herdis