Installation and updating procedure with plugin setup?

[etfz]

Hi,

Recently I'm looking into getting a plugins build going. I got a setup going, but only barely. I'm not familiar with building my own images from before. I followed the instructions here:
https://github.com/netbox-community/netbox-docker/wiki/Using-Netbox-Plugins

A few things of which I'm uncertain.

1. Probably a stupid question, but do I need to change anything in /env/netbox.env, normally? I don't remember having changed anything setting up my regular Docker setup.
2. Is SECRET_KEY meant to be literally "dummy" in the Dockerfile?
3. When do I need to rebuild the image?
4. Am I right in thinking that following the instructions while not touching plugin_requirements.txt or configuration.py effectively gives me a vanilla Docker setup?
5. Am I right in thinking I can (and should?) follow the instructions (starting at "Create a few files...") while merging the build and image bits from the suggested override file into my production override file, in order to convert my setup to a plugin supported one?
6. Lastly, but most importantly, what is the procedure for updating this NetBox/NetBox-Docker setup compared to a regular, non custom image setup?

Thank you