That article was immensely helpful for me. I fully understand resistance/current/power/etc but tubes still give me a hard time. Your explanations definitely filled in some holes.
Few things I still find confusing/have questions about:
-For grid voltage vs. plate current, the way I thought tubes worked is that the electrons glow off of the cathode, go past the grid, and hit the plate. This would make current flowing from plate to grid. Also, I thought that a more negative grid would repel the electrons flying off the cathode thus lessening current. In your explanation, both these directions are backwards. Am I missing something, maybe something to do with electron flow vs current flow?
-What determines the rp? Can it be modeled as a resistor somewhere in the way that output resistance can? I can't quite picture where the resistance is in the circuit.
-How does a choke swing voltages over the PSU voltage? I guess this question is more in a physical sense.