To the OP, if you do not have an owners manual for the Escalade here is a link to it.
Owners manual, 2016 EscaladeReferences, page 216, Tow Haul Mode on the transmission shifter. You certainly should be using this.
Pages 253 to 262 is the section on towing.
You need to determine what options the vehicle has such as StabiliTrak, Adaptive Cruise Control, and Parking Assist (both should be turned off or disabled, per the manual)
Factory Tow Package? Doesn't mean it came with a hitch, but would have wiring for the 7 pin connector on the rear and a connector under the dash for the brake controller. It also may mean heavy duty cooling for the engine and transmission, possibly a larger alternator, etc. You dealer (probably the parts counter) can take your VIN number and print out a build sheet that lists all the options installed on your vehicle.
If you have 4 wheel drive and either 20 or 22 inch wheels, your towing capacity is somewhat reduced.
The manual may answer some of your questions with regard to the hitch, such as WITHOUT a Weight Distributing Hitch your maximum tongue weight is limited to 600 lbs while it is 1000 lbs with a WDH. (and you may be over that.)
As already mentioned, you need an electric brake controller in addition to the WDH, and other stuff. Teknosha products are great, The P3 is good but a little excessive in that it has memory for four trailers. Only dislike about the P3 is the bright screen that dims, but not enough, at night. Its on all the time, trailer or not, somewhat annoying. Lots of good controllers out there.
P3 controller and harness for Escalade with factory tow package.Charles