How much resources are needed to create and maintain a site like Facebook

Answer 1

Resource wise, you would need a webhost and a suitable domain name. The languages you need would vary between the following: JavaScript, CSS, PHP, HTML and If needed, MySQL.

Webhost wise, you would need a large amount of bandwidth and a gargantuan storage space for all the photos, posts and profiles that will be used.

**Unnecessary** You may want some Graphic Design also.

Answer 2

I'd see both relational and non-relational server environments packed in clusters on all the continents and taking up to 20% of the submarine cable bandwidth ;)

Answer 3

shortly are the following:
1. programming skills
2. security skills

1. in programming skills you should know both application and server side programming language ie. php, mysql, ruby, c++ , HTML etc. But on the same case when you want to build a site like Facebook its better if you have an ability to develop your own language just like how Facebook do (they develop hiphop for php wich its combine alot of language)

2. in another side you should be aware on different aspects of security such as you should know all about back-end and front-end so as to protect your network layer against attackers.