AEBS Disks and Folder Security/Authorization/Global Bonjour

Im running a My Book Pro II WD 1TB HDD off of my AEBS, formated mac extended journaled. What I would like to do is set up different accounts that will have different access to folders. For instance, I would like admin access to everything including personal documents, then a house access that only can view media files, and then a guest access that I can give to people to sign into through WAN that will have limited read ability. I see I can create accounts on the airport utility, but what do I do after that to do these restrictions?

Also, global bonjour. Apple's very detailed and explanatory manual doesn't talk about global bonjour for airport disks. Does this allow me to have a website name or something that redirects to my ip address. Would this allow me to sign into my AD off of my university's campus? I've tried putting in my ip address, but it doesn't appear to get through our firewall. Note, I don't believe I have a static IP, but apparently it's been the same IP for the last 3 weeks.

 

I've used houdini to hide folders that I don't want people to access, although if they're smart enough, they can find it. What do I do for folder control, and please, what does global bonjour do?