I've been doing lots of research and have found that you basically have two options:
a) Pay by usage of bytes transferred (Depends on amount of users who log on, how long they listen to your webcast and at what quality.)
b) Pay a flat monthly fee by limiting the amount of listeners at any one time as well as the maximum bitrate quality of your stream (8k, 32k, 64k, 128k, etc.)
These are considering you are streaming 24/7.
You can also upload canned material to their server for "on demand" listening. This is not a bad option as it is cheaper and you can have live stream "windows" in which you can cut in for a live show.
Personally I want to get the 24/7 service so I can cut in whenever I want.
As far copyrighted material, yes you are supposed to pay licensing fees to the respective licensing entities.
The four US associations:
www.riaa.com (Recording Industry Association of America)
www.soundexchange.com
www.bmi.com (Broadcast Music, Inc.)
www.ascap.com (American Society of Composers, Authors and Publishers)
And also:
www.sesac.com (Society of European Stage Authors and Composers)
So far these are the service providers I have found:
www.live365.com
I had checked this one out as one of my friends used to stream on it. With it's popularity, as you (Anon) had mentioned, it has gotten very commercialized. They offer a Pro Package with royalty fees included for all the aforementioned licensing entities. If you opt for a Pro Package without the Royalty Fees included, they make you sign an affidavit and show proof of licensing. Their "beginner" packages are affordable but I believe they are all limited to uploads only, no live streaming (correct me if I'm wrong.)
www.surfernetwork.com
"Start webcasting for only $150 a month" Found this site a little unstructurized. Their packages are a little "loose." I like to know exactly what I'm getting for my $$$
www.audiovideoweb.com
More affordable for live webcasting. Very user friendly, straightforward and informative webpage.
www.audiorealm.com
Very extended webcasting community and so far the most economic. They offer a free "upload" account and very cheap streaming.
All these I believe offer free encoding software as well as listener stats and such. AudioRealm offers their "SAM" automation program.