Clarification concerning actions performed by Installation Wizard on 1st run

I followed a tutorial on how to setup a NAS with RAID that used NextCloud. Everything went well, but the 1st run indicated that sqlite wasn’t suitable for real use. There were some other issues too, so I adjusted the process to suit my own situation. Everything is working fine so far. I’m up to the point where I need to login for the 1st time and let the setup finish. Before I run it, I’d like to make sure I have everything like I think I do.

  1. I intend to create an admin user that is the same as an existing sudo user on the host machine.
  2. I intend to make that same existing sudo user the mariadb user.
  3. I left the last field of the database configuration as “localhost”.
  4. I set the data location to a directory on the RAID that hasn’t yet been created.

Now the questions:
For #1 & #2, since the existing user is the only human user on the host machine, is that going to be ok?

For #3, will that “localhost” setting still allow access from outside of my local (private) network? (In other words, does that mean that people who access my NAS from the internet will interact with NextCloud and NextCloud will interact with the database as necessary internally?) (Hope that makes sense.

For #4, Do I need to create the data directory prior to running the Wizard, or will it be created and populated by the Wizard? I intend for the data directory to be /mnt/nextcloud/data/. So do I need to create the data directory or just /mnt/nextcloud/?

Also for #4, Do I need to chown and chmod the data directory or will the Wizard handle that?

Sorry this got kind of long, but I want to get this right the 1st time through so I wind up with a very clean build when I’m finished. I don’t have any problem working from the shell or performing some of the configuration tasks as required. I’m just not 100% certain what some of those tasks are and at which point in the build process I should perform them. Thanks for any help.