send a job to a printer via a script

[Artturi]

Hello,

I would like to setup a solution that would enable students using their own laptops to print on our school's printers. Would work like this :

1 - student connects to print portal
2 - student uploads document to be printed : printer portal stores job info, document and generates "print code"
3 - student then locates the nearest public printer, and inserts "print code" on the computer beside
4 - computer connects to print portal with "print code" : print portal sends the document to the printer connected to computer

I'd like to know two things :

a) Do you know an existent system that works that way, avoiding us a development ?
b) if not :
 - how could step 4 be done ? (which command to run ?)
 - what format shoud the student use in step 2 ? (pdf ? ps ? other ?)
 - would it be possible to setup a virtual printer on "print portal", which could easily be installed by the student on its laptop, and which would produce the right format for previous step ?

Thanks in advance for any help,

Regards,
Artturi