>>4 Here are a few tipps, that I wished I knew at that time:
1. Using any of the above for web development doesn't mean you don't have to know HTML or CSS (when a page is developed try it on validator.w3.org)
2. don't buy a book, it costs and is not that satisfactionary, for PHP, Javascript and MySQL there are plenty of resources online, how-to's, code examples and more... If you can look for a wiki, these are continuasly updated!
3. Is PHP so important? Because if you're on the learning curve, i'll suggest ruby or python. Because they are easier to understand and easier to implement, making it possible to implement top notch programs (optimised and all that)
4. Also consider running a platform to easy thing out (php pear, django or web2py for python or rails for ruby and many more which I haven't tested)
Hope this tipps helped you