2) Hosting is cheap so your parents will probably let you use their credit card.
3) It's so approachable that it can help you get started with programming so that some day you can move on to better languages.
PHP also offers a build in function for nearly everything.
The main drawback of PHP are the tutorials, using mysql without the i, and teach how to implement a website that is vulnerable to SQL injection.
PHP's advantage is "apt-get install php5", copy your .php files in, and you're done.
For example, when I search for "PHP function list", I not only get a function list as the first item, it's an amazingly comprehensive list. The hurdles I've had so far, I've been able to jump over them quickly (quicker than in any other language I've learned) if only because the community support is so good. Usually a simple web search finds the question and answer I'm looking for. I'm pretty blown away by the sheer volume of good info on PHP.
Python is my second choice. There's a lot that I prefer of it, over PHP, but I find that in general its hurdles are higher.
Having developed many industrial-strength apps using less-capable languages, I'm confident I can do the same in PHP.
Between the above and the huge range of existing PHP projects, I always install PHP regardless of what else I'm using.