the userNameSwitch.php is only necessary if you want the name that displays on the graphic to be different somehow from your actual LFS user name.
for example, one of the guys that is using this registered as mini z, but later decided he didn't like that name, so changed the ingame name to rotary power. but if you try to pull rotary power, nothing comes up. so this is where the userNameSwitch.php file comes into play.
it uses mini z to pull the statistics from the LFS servers, but the name that is displayed on the graphic is rotary power.
like wise, i'm assuming your LFS username is banshee56, but if you wanted the graphic to show [CORE]Banshee56, you'd use the userNameSwitch file.
also, the name variable is case-insentive, BaNshEE56 is basically the same as banshee56. the only difference between the two is how they are displayed on the graphic. both pull the same stats. make sense?
and as for each teammate, all you have to do is change the username in the url (and the template number if you wish, but not necessary).
now, for the ident key...what i'm doing right now is just using my key for all my friends that are using the script (they are just linking the code on my page and putting there username in). Which is fine, except for the "who's online" page that displays all of these graphics on one page, because the LFS server that the stats are pulled from only allows access from one ident key every 5 seconds...so on a page with 6 graphics, that could take ~30 seconds to load them all.
but i just thought of a solution to that. so for now, just let them use your ident key (they won't ever see it), and i'll get a new version out later today or tomorrow (or you could purchase some credits and go with premium access, which has no delay on multiple access.
in short, no, only one folder.
for multiple users, just do the following...
http://your-host/check#.glyphon.jpg
http://your-host/check#.banshee56.jpg
http://your-host/check#.Victor.jpg
...
and keep me updated as to what happens with the online graphic. (make sure its permission is set to 644).