I envy you.
Advice? Here we go...
1- That space in the top right corner? If i read your plans properly and that is your furnace area that is walled-in, that section would be surrounded by 3 hard walls. You'll likely neither want to throw into that area, and if you are in there allready you'll want throw out of there. Also, your kamiza will be centered if you only do 12 mats, as well as being cheaper. Also, you will likely have bigger sense of space without that corner. You can always add those 4 mats later and fill in that space. In fact, I would extend the side closest to your stairs, and perhaps shift the whole thing towards that bathroom to clear the furnace-room wall and corner; might skew the centering with the kamiza, but you could fashion a false wall to shrink the kamiza space and shift it left.
2- I think the kamiza should be on the north wall, but could be completely wrong on that.
3- Mats; if Zebra's are the ones we have (has tackie, grey, waffled foam on bottom), and if you lay them down tight, a simple border should keep them from shifting (see http://www.zebramats.com/matframe.html
). Shifting only happens during really engertic practice, and we put our mats down and take them up each class, so we are only relying on the rubber underpad that comes with each mat. The spaces are really quite tight and low-profile.
Under the mat; try the mats as they are, and if you need to build a suspended floor you will know for sure (thereby also differing some of the cost to later). Direct on concrete (which we do) can be pretty hard, as many visitors have mentionned.
Number of mats; minimum is 3 for 2 people (your circles will tighten up!), 6 is comfy, 12 is luxurious, so I think you are good with the number you have.
Got any more pictures of the actual space right now?
Keep us posted, and good luck.