Where are the printers located? How can I find out where a given printer (say, lw7) is located? How can I find out what a printer is called, that I know the location of?

A lot of information about printers, including location, is stored in the file /lusr/share/etc/printcap -- you can look there for the location of a specific printer. You can also run man printers for usage and location information about the public printers.