Answer 1

You can do it with literally any programming language, php is a good option, and javascript also.

Answer 2

Yes it‘s possible, that is exact the way, how Content-Management-Systems like WordPress manage the contents.

Answer 3

This is a very common design pattern, in fact most websites work this way:
-front end (on the user's machine) that is shown to the user (UI)
-database that stores and serves dynamic content
-back end (on the server) making the connection between the gui and data layer and performing additional computations

Answer 4

For pure database access a server-side language like PHP is essential due to security issues (paths, login names, passwords ...)