Not on the MBA. Apple has not allowed 64-bit booting on MB or MBA to my knowledge. I tried when SL was first released. Even though hardware supports it, Apple doesn't on these two "consumer" Macs. Read about some third party utilities that can force it. Honestly with all the problems with those who are using 64-bit kernel, I believe OS X isn't truly ready for it. Apple has failed big time in my book!
Going to these kernel panics... I haven't had a single kp, ever on a rev B/C MBA. Not in Leopard nor in Snow Leopard. I have never used CoolBook either. I find no need on a rev B/C to use it.
Some have mentioned FireFox over Safari, but Safari is much much faster in its latest 4 release. I haven't had any problems with Safari.
I don't really have any clue what's happening here. I sure wonder if it's a common app you're all using if it's only happening in Snow Leopard or if it's a hardware issue.