[thorax]

a) Probably start trying to write a site you want and learning from there-- with a background in other languages it's more about "I know the language can do X-- let me search for something like it". When using PHP you can often just google "PHP equivalent of " whatever function you know in C#/Java/JS and there will be some corresponding example to use.

b) I like NuSphere PhpEd even though it isn't free. Some people like Netbeans IDE for PHP.

c) I love CodeIgniter. Very fast, MVC, some of the best user guides for any framework, just very solid all around. Go with it initially-- I know many PHP developers who got started there and have grown to be some of the most productive web coders I've ever seen.