Well, a few good questions there..
But, I have to draw you now into another theory/idea...
And one, that I feel, could be so much more easily provable (and I mean without going down the Dimension route etc.)
I have recently come up with this idea after reading another thread elsewhere and it gave me some ideas so I put fingers to keyboard and began writing and researching. What I've currently found has been knocking me for six, almost. I am rather astonished with the amount of exisitng information and new info that is currently widely available, I'm surprised that nobody has linked it all together before.
The idea is that DNA leaves behind a trace signature, or more simply, a copy of what it once was. This 'copy' is the information that the DNA contained.
To fully understand what I'm talking about you'll have to take a quick little trip via a link to this thread;
Is DNA the influence behind some paranormal activity??, page 1
There's quite a bit of info there, but I'm hoping that all the evidence so far collected is going to be part of the proof that ghosts can and do exist.
As we speak, myself and some of the team I work with are building a few test devices to be used in the field in order to test out some of the ideas and principles explained in the thread i've linked to.
Onwards and upwards as they say.. One day someone will crack it and we will all know for sure (not that many of us don't already know, but you know what I mean )