Doesn't AOPA's flight planner already do some of the same things you're talking about?

A computer science guru friend of mine suggests that you use Java as the programming lanuage, and Netbeans as your programming environment. I personally don't have any idea of what he is talking about, that's why he's the guru and I am not. Here are the reasons that he would recommend going this route, Java is platform independant and can be run on several different operating systems. Java has a well developed library and is threaded at a core level. You can set it up for a stand alone ap or run off a web page.

Netbean is created by Sun who created Java and is built to work with Java specifically. It also has a GUI builder.

Hope this helps a little. If you have any other questions you want asked, PM me and I'll pose the questions for you and try to get answers.