No, all stored models are always visible to all printers that share the directory. But I mean model folder not the print queue! Print queue is always per printer as that is what you are planning to print on that particular printer.
Server uses the folder /var/lib/Repetier-Server so it has as much space as the drive occupies. You can move it somewhere else and make a hard link from /var/lib/Repetier-Server to your real directory if you want and have more space there.