I have a number of Jockey boxes, all using cold plates (2 pass, 5 pass, and 6 pass).
I would highly recommend replacing any tubing that came with it.
I would also recommend you to use BLC rather than PBW to run through the lines, let it soak, and do the same with the shanks and faucets. The rest would be done as you said, water, then starsan.
While you are flushing the lines, make sure to keep an eye to see if there are any leaks, and address those as you go. You definitely don't want to be serving at your event and trying to fix a leak (I've been there and done that - no fun at all).
Also, after you have used it, make sure to flush out all beer from the lines, and let the inside dry out. Mold grows amazingly fast inside a wet cooler - I've also made this mistake numerous times, and had to replace the coolers a couple of times.
I use chrome plated brass hardware for my jockey boxes (at this point, probably just brass), but I don't mind since I use them for events where the beer is flowing pretty quickly, and only for a few hours. If you have the money though, you can think about upgrading to all stainless hardware.