I too wondered the same about the 2/3rds climb requirement but you'll find that you should use the 185 RSWT data for cruise levels up to and including FL310, and use 235 data for FL330 and above. My understanding is that there is to be no interpolation between RSWT levels at any time.
Assume instantaneous descent for DP and 2E ops, the "descent to lower level" applies to a yaw damper level or for a descent from cruise down into a holding level etc.