1. On this page you can see the diagram (see the "Serial LEDs output capacity" header):
2. Any pin that is allowed in the configurator can be used, up to #69 (A15),
the coloured 30-37 are reserved for directly connected 7-segment displays and PWM driver.
For DM13A you can select any other.
4. You can have at least up to 20 outputs used for serial LEDs.
5. You can combine the number of used drivers - for one pin you can connect one driver (up to 16 LEDs) , for another pin - 3 drivers, and so on (up to 4 drivers or 64 LEDs max.) -depending on your system, how is more comfortable for you.