Coolant Refill

I am in the process of draining and refilling the coolant in my 2000 4.0 S-Type, following the procedure in the Jaguar Technical Information System (JTIS). The draining procedure (303-03) results in draining of somewhat less than 5 quarts. The system capacity is 10.5 quarts so this accomplishes removal of less than 50% of the old fluid. There is no block drain mentioned. Has anyone else been through this? Looks like I'm going to have to alter the procedure, e.g. remove thermostat, unhook heater lines, etc. to get better results. Also, is the heater air bleed located at the end of a rubber tube next to the expansion tank 7 is it opened via a slotted screwdriver?

So far I'm way less than impressed with JTIS info.

Thanks,
Okie Cat