I see what you're saying. Thanks for reporting. I've never used that alternative before. I believe it's coming from this line where it excludes the docs folder so the symlink is no longer valid.
I've made a ticket at https://lab.civicrm.org/dev/core/issues/1393
In the end, I'm not sure what the problem was: either Adminer when either exporting and/or importing; or, the table collations being latin1_swedish_ci, even though both databases used the same collation; or even a conflict between the very old linux version and newer MySQL versions on the server.
But I exported using mysqldump via SSH while forcing UTF, and ...
On which forms do you wish to add the fields/logic?
I feel like there are two questions here:
1) How to build an arbitrary list of options from a third-party source of data (Drupal)
2) How to set the value of one field based on the value of another fields.
For (1), arbitrary lists, you can look into hook_civicrm_fieldOptions, which can dynamically modify ...
The difference between readonly and disabled is a common thing with HTML and forms.
See for example https://stackoverflow.com/questions/7730695/whats-the-difference-between-disabled-disabled-and-readonly-readonly-for-ht
It's on purpose that it removes the link to the user when you delete. It was added years ago here: https://github.com/civicrm/civicrm-svn/commit/3d9843c5912cb9d77e557b4a8cd4ef711f2cdcbb
and seems related to deduping https://issues.civicrm.org/jira/browse/CRM-6861
But yes Civi will reattach them once you do something that triggers the matching which is ...
I would check what is happening by setting up a Profile with the simplest possible profile eg just First and Last and Email
That will help rule out the issue being related to any of your Fields or permissions related to eg Custom Fields.
I am quite curious about why you are asking this question. My advice would be to install only modules when you have functional need and those modules solve them for you.
It might be even that a module which is used often is completely useless in your context. Or that it breaks other needed functionality.
Having said that the masquerade module is very ...