very easy .I bought my wires on eBay ,,,the trailer harness plugs right into your lights no cutting at all
I took mine in to Uhaul to have them install a tow bar and light harness. Mine didn't come with a light harness, they had to install one.
The towing capacity for the Nissan Quest is 3500 pounds.
Have you looked under the vehicle? I'd be surprised if the wiring harness wasn't already there and taped up under the vehicle. Barring that, most business that sell and install trailer hitches will also install trailer wiring harnesses. If you're a DIY, go to the local auto parts store and ask. They probably have the wiring harness you need all setup to plug into the manufacturer's wiring harness.
The maximum tosing capacity of the 2014 Nissan Rogue is 1000 lbs..
5500lbs
5000lbs
3500 lbs
3000kgs
2000
3500 lbs towing capacity according to endmunds: http://www.edmunds.com/used/1990/nissan/truck/1552/specs.html
1450kg
The maximum tosing capacity of the 2008 Nissan Xterra is 5000 lbs..