In order: yes, and nuffink but not having a TFT display available. There is no electrical reason not to do so. If you have a spare TFT display (lucky you), replace the FSTN display forthwith, or sooner. Fortunately, Apple had worked out a better way to get the display cable through the clutch compartment by the time of the 500 series, but you will have to exercise care in the disassembly. The flexible PCB that is the display cable coils around the clutch mechanism, so, softly, softly, catchee monkey. And mind that dratted central cover over the microphone. It gives a new dimension to the meaning of 'perishable'.

Then all you will need is a 603e/100MHz, 117Mhz or faster daughter card for total satisfaction (as long as you also have a 32MB RAM expansion card).

de