You dont need to worry about hosting for mirc
you can download from
www.mirc.com
Setting up a room is very easy but having it permant you need to have something sorted for you.
I havent done anything with MIRC for years but years ago you used to have to have a certain amount of people wanting that room and then apply to the MIRC hosts so for example
it would be acorndomains.speeddemon@mirc or something like that
Once you have a certain amount of people backing you then it would be a permant room.
You could assign moderators than have the power to boot someone out of the room etc, but when I was a mod we spent so much time kicking each other out of the room we didnt worry about anyone else and that was about 5 years or more now.
You can also have the bots in the room that welcome people to the room and also post up greetings every so often, depends on when you set them to go off.
They can have filters to make them talk as well, so if someone swears you can have the bot say wash your mouth out with soap.
It would be good fun but you deffinatly dont want a web based java script chat room as thats slow and increases your bandwidth.