Which comes first, the trailer or the hitch system?

After owning 3 TT's I would skip the EAZ lift and get one with built in sway control. Like an Equalizer type or what I'm using now, a Blue Ox Sway Pro.
The 'All in one's' are easier to use as you aren't dealing with two separate systems. No unhooking to backup like the EAZ lift package in your link.

Most all dealers will set you up initially. I bought my own hitch off Amazon and took it in when I picked up the TT.