Answer 1

what do you mean "web programming languages"? For a Web pages/apps you have need:
- A way for represent semantic content and this is the rule of HTML markup language
- A way of styling content in simple, extendible and indipendent way and this is possible with CSS
- A way for make interaction between contents, user and other resources and this is madeds in Javascript language
- Javascript do client work but other works can be do on server side and this is the rule of any programming language that can handle connection between it and web server and client but most popular and accepted is surely PHP