1. Your Qtc and Fs will be a little higher. But you can add about 1/2 pound of fiberfill (use half of a 20 oz bag from Wal-Mart) and that will counteract the 10% smaller enclosure.
2. This is a complete guess on my part but based on the picture of the coil you are using. It looks similar to the one that PSI used on a sub of mine. I asked and he said it was about 22mm. You are going to need a bar grill system. If you are going with a waffle grill then you need some pretty big stand-offs to move it away from the driver.
David only pulls T/S parameters when you pay for them. He has to break in the driver for a few hours and then go through a detailed process to pull them. If you need them now, you need to find someone with a Woofer Tester from Parts Express.