The old Mac software can't deal with a volume of 2G or larger.
You don't have to make a hard partition. I ran into this about a year ago, made a temporary disk image file with some utility, mounted it, shared it, moved the files no problem.
Not many things are fixed by zapping the PRAM, but this could be one of them. Since removing extensions didn't work, you should put them back; it's not obvious which ones are required for networking.
StyleWriter I and II work with System 6 and monochrome Macs. StyleWriter 1200, 1500, 2400, and 2500 use drivers that require Color Quickdraw, which is not available on any 68000-based Mac. I think the driver also requires System 7. The 2500 driver can be used with MacOS 9 and even works in...
The Etherwave AUI and AAUI dongles don't require any software and seem to work on anything that has an AUI or AAUI port. The Printer adapter, which converts ethernet to localtalk, also requires no software and seems to work on any localtalk printer.
The "Mac" adapter, sometimes called PB...
iTunes is not compatible with the sound hardware on the 6200 series. It seems to require a PCI-type Mac such as the 8500. I think you can run SoundJam MP which might be a suitable replacement.
Don't know the answers to your questions, but one of my favorite monitors was the 12" monochrome in the same form factor. It did 640x480 and was extremely lightweight. I had two of them, but both eventually developed jitters.