I think .ogg and .mp4 is usually best. The recent portable audio players usually support either one. Plus, they're usually like 1/8th the size of your typical mp3 (hence, mp4, a newer standard) without any big loss of quality or anything. Then again, there might always be something better since I haven't messed with audio formats for a while (but will soon again when I might start doing a little cinematography or something).
As for where it could be, well, there's a handful of those cheesy free hosting plans. However this looks like a decent free host:
http://www.oxyhost.com/ (I haven't used the service. Perhaps you could be my little guinea pig for that ;P) And honestly, feel free to request someone to code a layout and such for it. You could probably even just use Wordpress, Drupal, or something else instead of having to depend on someone for website changes and to keep it simple.
But yea, you could probably deviate even more along with a podcast if you plan to get a basic web server.
