The rack comes with all pieces except the Q-towers and the Q-clips (well and bars/locks/etc). The car-specific Q-clips will fit right in to the stretch kit pieces.. nothing additional is needed.
I had this on a Mazda3, and I believe the clips were flush with the car. They shouldn't be uneven or pulling, or it could damage your roof (and perhaps make the rack less stable). I once took detailed pictures of a rack I was concerned with the fit on, and emailed the pics to Yakima. A fit expert responded, and worked me through the problem. Great customer service. You could also go to your local rack store (REI/EMS/Rack N Road), and they could help you with fit.
If you use an open roof rack for the snowboards, you should be able to get away with it, not sure about the bike racks though. Measure out the bar spacing and then measure out the bottom of the box/rack, and if they don't line up you will need the stretcher.
This is only the stretch bar, the crossbars and Q towers are all sold seperately. That is why I am asking if I really need this stretch kit for my car or if I can do without one (Acura Integra 3dr). Just trying to keep costs low for me since the other required components already cost a lot for me.
Go to www.yakima.com to see if this item is needed for your rack. If it is, don't sweat your short roof line, as this will do the trick. It's easy to install for anyone that can read directions. Highly recommended.