According to this: http://www.everymac.com/systems/apple/p ... eries.html
there is one standard serial port.
1.)It should be possible to build a NULL-modem connection to some PC with a serial port.
The Mac and PC serial ports are compatible but you may need a home soldered cable.
File transfer can be done with ZTerm on the Mac side.
I do not recall the names of the terminal software for PCs right now, but there were many.
2.)As far as I remember, you just had to plug in a LocalTalk cable and its dongle in the Mac´s serial port,
to have your Mac use LocalTalk. The Macs were daisy chained like those with BNC ethernet.
You will need at least one other computer capable of LocalTalk, of course.
A solution with PCMacLan would work with a LocalTalk connection and WIN98, but it would require
a LocalTalk adapter too in the PC. I doubt such an adapter can still be found.
3.)Maybe you should look for a 68k version of Dave, to connect to a Windows network.
Someone else might tell you about Dave, I never used it.