Drupal 8.x

I am new to Drupal. I have a working webapp in PHP/MySQL which I am trying to port to Drupal. Here is my problem:

In the webapp, I have a table called Patients with a DoB (Date of Birth) field. The input form takes in information as "Age" in years and months, and inputs an approximate DoB by subtracting from current date (This is because most of the patients, where this is used, are not aware of their DoB).

I install drupal 8 on a RHEL 7.7 VM.  After the installation, I go through the process of connecting the server to a mySQL 5.7 database.  After entering the credentials and arriving on the last page to configure the site, when I close the page and attempt to access the sever again from a web browser, I get this error, "The website encountered an unexpected error.

Hi,

I am trying to add a link to my Main Navigation menu. The link to my custom page looks like /text/{textid}/download. How can I add such a link to the menu?

Thanks,

Is it possible to create a media type programmatically?
I would like to use the already existing MediaSource "image" and do not use a new MediaSource.
Basically like the UI (/admin/structure/media/add), but programmatically?

Or does anyone know a plugin for Drupal Console that can be used to create Media Bundles/Types/Entities?

Hi

Does anyone know of a module or feature that will automatically keep a detailed log of the changes I make to each node. This way if my client asks me "what did you do on Jan 7 2020? or what did you do for the month of March 2020?" I can go into their website go to the log and pull up the list. I'm using Drupal 8.