Hi Marco,
1) A multimedia/desktop oriented kernel like the one in 64Studio orhere: ftp://musix.ourproject.org/pub/musix/deb/kernel/n
I believe Musix now uses the 64 Studio kernel packages, so that's one less variable ;-) Ubuntu Studio is not going for a Molnar-style RT kernel, according to an interview with Cory Kontros I read.
The reason why this has not been made already it's a secret to me, and a even weirder one.
I believe it's because in the mainstream, audio on GNU/Linux has mostly been addressed from the point of view of a so-called 'consumer'. So distros have tried to solve questions like "How do I make my iPod work out of the box, so I can re-arrange my collection of Britney Spears downloads?" rather than "How do I tune my kernel and OS for maximum performance when tracking 24 channels over my ADAT interface?"
I believe free software has a role to play in providing serious, reliable tools to the people that need them, in order to enable and enhance their creativity. Among other free software advocates, there is an argument that says we need to chase the tail-lights of OS X and Windows Vista in providing a slick 'consumer' experience, which has very little to do with RT kernels or tools like jackd.
Cheers! Daniel