Re: cold start/rpm
Never waited for the RPM to drop on my '07.
The computer does the right thing when you go into gear, it isn't like the old days when you'd be slamming your drivetrain. The only warming up the transmission is getting is frictional; IIRC neither the WK nor WK2 has a radiator-tank trans cooler, and even then that does no warming until the engine thermostat opens.
Drive gently until you get up to operating temp, but other than getting cabin heat there isn't much of value that happens after the first 5 seconds of engine warmup. IMHO, of course.
2007 WK Limited 5.7L
2014 WK2 Overland 5.7L
And a few past Durangos