That's Wayne Piquet's work on Quads. He rebuilds them (after bombarding me with lots of questions to learn how). He's into different frames and lots of finish changes. Not my cup of tea, but style is subjective.
As to diaphragm resistance, most if not all modern ESL's charge the diaphragm through a high value resistor (10 - 100 megohms). This resistor is really responsible for maintaining constant charge operation of the panel. The panel resistance is measured in ohms per square. Square what? Exactly.

It's non dimensionalized, and the two penny technique is good to test to make sure your diaphragm is conductive, but not really useful to reporting an actual meaningful surface conductivity value unless you factor in the penny geometry.
Simplification alert:
You can think of the resistance as part of an RC network of sorts. you want the time constant of the charge movement to be slower than the lowest frequency you want to reproduce for linear operation of the cell. so you could get away with a lot more conductive diaphragm in a tweeter than a bass panel.
As to foam tape, there are a lot of different grades out there. The eurathane foam with acrylic adhesive seems to hold up a lot better than the cheap grade foams. Your friends at 3M have a lot to say about foam tapes.
As to graphite: It's hard to get a more inert material to coat a diaphragm with than carbon. Back in my pupal stages, I used to use graphite to coat ESL diaphragms. It works well and lasts a long time in my experience (that CO2 argument strikes me as implausible). But it's tedious and tiring to apply and you can easily rip thinner diaphragm materials. There are easier to apply coatings whose surface resistivity can be tailored to whatever value you want. I use about 10^11 ohms/sq for quad ESL57 rebuilds, and about 10^8 ohms/sq for DIY esl cells and ESL63 rebuilds.