Interaction between pulse and jack does not depend on configuration issues.
Added link for the bug report about pulseaudio not releasing card to jack
if jack starts, then there will be audio, if the user chose the correct device
There are no known critical dependencies for jack and pulse to interact properly.
They way jack is packaged for Debian/Ubuntu, only jack2 will be able to grab the card.
For this, you only need two packages. pulseaudio and jackd2
There are no known packages on Debian/Ubuntu that will let jack1 grab the card from pulse-
Added link to bug report on jack, and clarified that only jackdbus 1.9.8 suffers from this bug.
When installing jackd on Debian/Ubuntu, one may choose if to use realtime or not.
As an effect, /etc/limits.d/audio.conf may be named /etc/limits.d/audio.conf.disabled,
if one chose "no".
Added link which explains audio group issues on Ubuntu
I don't see the point in recommending other distros on a Ubuntu manual page.
Better in that case, to just recommend distros on a Ardour specific page.
How to fix issues with bugs
Moved info about Audio group on Ubuntu to a more suitable place.
minor edit
Added some specifics about which released are affected by gugs,
and which are not
Made the point of Ardour support for Ubuntu clear.
I believe this should be enough to point out what the issues are.
Added Dreamstudio to the mix of alternative Ubuntu distros
Removed line about jackdbus stop crash bug, which is no longer affecting Ubuntu 12.04 and later
Merge branch 'master' of https://github.com/PipeManMusic/manual
Added info about regionfade/crossfade as well as some cleanup