What are the two resistors doing in this circuit, and how do I calculate their value?
Do you mean figure 12?
They limit the current into the base of the transistor (R1) and provide a DC path to ground when the PWM device is not active (R2).
R2 you don't calculate, for R1 you need to know the gain of the transistor you are using and the current you want to switch.
- Am I right in thinking that while I can have an arbitrarily long chain of leds by supplying sufficient voltage, the maximum current through those leds (and therefore the ccr driver) can be 160mA
Yes, it is the sufficient voltage that is the catch.
What is figure 11 illustrating then with the use of a resistor on one ccr?
It is showing that the current you regulate on one CCR is mirrored by the second to double the current and split over two devices the heat dissipation.
If I need still more current than this, is there a better product or technique I could use?
Yes there always is.