Just a small point really, the ALT INTV needs to be activated in climbing but is it the same for reducing climb? on page 0.00.69 of the tutorial, the MCP is lowered to 2000 feet, but there isn't a mention of the ALT INTV button?

Thanks 

Only if you want to descend before the Top of Descent, when in VNAV.If you want to follow VNAV, just dial down the altitude window, and let the aircraft decide about the descend path it's going to take.

Thanks, I'll try that tonight