1. There's thousands of experienced PHP coders out there, so definitely grab some more experience and more complex applications before trying to compete in that field. You don't want to get a client that expects you to code a complicated PHP/Mysql app.

2. ASP.net is a popular one to learn, sure. Also check out more complex languages like C#, C++, and Ruby. Take a few programming classes if you can, as they will teach you best coding practices.

3. DW8 is a solid good start and should be enough for your needs right now. You can find free accounts that allow you to do small development work on them, or ones for a few bucks a month. If you have an old computer lying around, you can also load a copy of linux on it and use that as your dev server.