For installing on multiple computers it's possible to do fully
automatic installations. Debian packages intended for this include
fai (which uses an install server),
the Debian Installer itself.
The Debian Installer supports automating installs via preconfiguration files. A preconfiguration file can be loaded from the network or from removable media, and used to fill in answers to questions asked during the installation process.
Full documentation on preseeding including a working example that you can edit is in Appendix B, Automating the installation using preseeding.