I used it back in my Windows days. Out of the box, I think it's the only way to do rich text on Windows. Also (used to be anyway) one of the less resource intensive options.
You know, for when you've got Napster, Winamp (with visualisation), ICQ, and MSN all up and barely running. You don't want to have to run, like, WordPerfect at the same time! Your MP3s will start skipping :p
Can you format at all in Notepad++? I tend to use it for notes jot down in a rush or editing tiny scripts. For stuff that needs to look prettier, I tend to use Google Docs.
Yes and then some. It has built in support for a lot of programming languages plus allows you to add more. It also support extended and regex find/replace.
They created WordPad because of antitrust issues and never changed it. Try opening a Word document created by a recent version, it's pretty useless today.
Notepad rules though, it even got UTF8 support recently-ish! /s