it doesn't matter at all as far as SEO is concerned. .com is always preferred just because it's the one we always think of.
domain name not depending. but you have to think about your customers. from US then .com or UK then .co.uk much better for SEM.
If your potential visitors would expect and remember a .com better, then you might choose a .com But as Loco points out, its laughable to think that one would have an seo advantage.
a good domain helps but i have had success with .TV's .BIZ & .US, its the amount of work you do behind the scenes that helps more
AFAIK,SEO is not depend on domain extension. But depend on the keyword of the domain plus the content of site.
The one who suit us is the best domain for me, because we have different taste in choosing domains! Regards Alfred