If you want to have some fun; open up some the cab file gauges that come with FS9 (and some of the downloads) and take a look at them. The bitmaps and XML files are pretty self explanatory (where they get ther data and how it's displayed). You can modify those.. or.. write some from scratch.

It takes some level of programming proficiency, but it's a blast. (and free).

I'm not sure what you're asking. XML is written in,, umm ,,err.. XML. I guess it's similar to HTML (been a while since I played with that) and kind of resembles C or assembler.

You can use an XML editor (free download if I remember correctly).. but I find it WAY easier to just open an existing XML file with Notepad; delete it all if you're writing a file from scratch; edit if that's all you have in mind and then save it from there and rename if needed.