There is nothing related to web development that you can do in other languages that you can't do with PHP. That should suffice for your first question: Do not r

There is nothing related to web development that you can do in other languages that you can't do with PHP. That should suffice for your first question: Do not rewrite any of your apps. If you want to learn another language, there are tons of stuff you can do with Python, from numerical programming to openGL. There is a widespread opinion that PHP is not as sexy as other scripting languages, and that it is too domain specific. That may be true. There is another opinion that with PHP you can only write spaghetti code. That one is false, it's up to you to organize your code. I 've been maintaining PHP scripts for years and didn't have that problem. Plus achieving good performance is easier with PHP, and that comes handy with high traffic sites. I like python for non-web projects. If only Android or iOS was written in python.