I honestly don't remember where I bought mine...I just figured out which one I needed and found a good deal. Yes it came with instructions and the damper I bought was all inclusive...nothing else to buy. Looks like these guys will take care of you.
As for the torque spec, here is a link to get a free service manual:
Kawasaki Service Repair Manual Download
This is your bikes bible. Get to know it. :nerd:
If you just don't have the cash for a new unit some guys are fitting oem units from other bikes (think newer 10R) onto this one. Some people chuck the oem units in favor of an aftermarket unit and you can probably scoop up the old oem one relatively cheap. Sometimes the reason why they get rid of them is because the oem units aren't valved correctly to give proper damping...lawyers and all. The unit can be revalved fairly cheaply. (Sorry I can't remember right off hand where they were getting them done.)
Just take some time and get to know the bike and really scour the forums. The search engine here is kinda meh but look around and you can find some very good info. There are a lot of knowledgeable people here...and while not nearly as active as this place used to be there is still a wealth of info to be had.