What are the key security risks of using PHP or other scripting languages for financial web apps compared to Java?

Here is a cross-question that I answered on Quora and cite various PHP Security related links, specifically on how to code better in PHP (with security in mind).

If you are going to be coding in PHP, the attached resources (links) provide a great starting point to secure your code (for security purposes) when deploying applications with PHP.

How can one learn about hacking and security whilst building an E-commerce website?