1): more or less. The d-rest needs to occur when the yeast is still working and in solution, or it will be useless, but after the yeast has finished making pretty much all the diacetyl it's going to. So toward the end of fermentation.
2): 65-70 will be fine. Depends on how vigorously it's still fermenting, buy anywhere in that range will be pretty close.
3): the point of that is to help the yeast finish off fermentation/cleaning up, I think. Rack and cool after fermentation is fully completed, and it won't be a big deal if you cool it quickly. If the beer still isn't finished after the d-rest, it would be ideal to slowly bring down the temp as fermentation finishes, but you need to judge if the yeast will tolerate that. It may be best to try to time the d-rest such that the beer will be fully attenuated by the end of it; wait an extra day or so if necessary, then rack and lager.
4): There's plenty of waiting that will happen during lagering. Unlike with ales, that's where things smooth out. I wouldn't think this is necessary, or even necessarily a good idea; leave it in primary longer if primary fermentation is taking longer, not otherwise. And certainly don't d-rest 3 weeks after fermentation stops; it will do practically nothing.
Leaving in primary longer is a good idea with ales, as they a) aren't cold conditioned for extended periods, usually; and b) are fermented at temps where a lot more off-flavors can develop. Let ales sit at ale temperature longer; let lagers sit at lagering temperature longer.