A hardware handshake null modem cable and a terminal programme on each end should do well for file transfer. More convenience you can have with applications like Stargate, providing drag and drop file transfer in watched folders (Mac and PC Freeware available, Linux support unknown). It works like a charm. A list of suggestions that may lead to something useful for you can be found here: http://www.macwindows.com/peertips.html.

The page mentioned above also guides to a method of setting up a LaserWriter Plus (serial port only) to work directly connected to a Windows computer (again, using a null modem cable). The SE could probably access a PostScript printer via Ethernet using a SCSI-Ethernet adapter.