1. I've heard the M50ti speakers and they're pretty darn good. I think you should decide this. Look through the listing below and see if you can find anyone in your area with M60ti speakers that is willing to let you come over for an audition. Also remember that Axiom will let you try out the speakers for 30 days in your home and if you aren't satisfied, you're only out return shipping.
http://www.axiomaudio.com/boards/showflat.php?Cat=&Board=Auditions&Number=76567&page=0&view=collapsed&sb=5&o=0&fpart=
2. Probably, but the folks at Axiom would be the best resource to ask for this question. They'll give you the straight shot. Here's their number: 1-866-244-8796
And their hours: 9am - 11pm Mon-Fri, 10am - 9pm Sat and Sun, EST
3. You wouldn't want to mount them directly to the ceiling, though you might be able to get away with a bracket mount. However, it wouldn't be my first choice. While this isn't mounted on the ceiling, it gives you an idea of proximity:
4. Possibly. If there is a way to place your center channel below the TV and point it up towards the listening position, this would be preferable to behind and above the TV.
5. Maybe, maybe not. To find the right place for your subwoofer will require experimentation in your room. It might end up behind the couch or somewhere else, but I can't tell you just from looking. Check out the articles found
here to send you in the right direction.
6. Because the living room area is shared with the kitchen, you need to consider this when shopping for a subwoofer. The PB-12ISD might be adequate, but again, call the manufacturer and see what they think would be best for you. Remember, SVS also sells cylinder subs. Here's their number: (703) 845-1472, hours 10-6 M-F, EST.
7. Your surrounds are out of place. Surrounds should go to the left and right of the main listening position, and perhaps a little behind. If you decide to upgrade to 7.1, the rear surrounds will go in the approximate positions you have illustrated above. For more into on position, check out these articles:
http://www.audioholics.com/techtips/setup/loudspeakers/loudspeakerplacementguide.php
http://www.audioholics.com/techtips/setup/loudspeakers/hometheaterspeakerlayout.php
Overall it seems like you've made some pretty solid choices. As far as speakers go, don't sell short your local dealers. You may be able to find something in your budget that you find you like better than Axioms (assuming you auditioned them). As for subwoofers, SVS, Hsu, and the upper end Axiom subs are basically unbeatable for value. You won't be able to find something with comparable price and comparable performance locally.
I noticed you're doing wiring in your house. What do you plan on using for this part of the project? What about the electrical going to your equipment area?
Oh, and of course, welcome to AH!