Is there an huge requirements for PHP developer?Is it necessary to have Apache server for PHP?
That depends on the area where you want to work. In general there is always lots of work for a good and experienced PHP developer. But PHP alone is not enough. You should also master (at least) a couple of other languages (JavaScript, Java, C++) or acquire database SQL like and DB administration skills.
For the long term it is almost mandatory to acquire more general programming, like OOP and design, skills and broaden your operating system knowledge, i.e. not just stick with client OS'es, but also look at Unix/Linux, OS/400 etc.
PHP will run on any server (Apache, Windows, etc) as long as that server supports PHP.
Ronald