Perhaps we are understanding this in a different way for example - physical death is a kind of separation Martin - granted only a temporary one (IMO) but still a separation of sorts. Only a small number of us can still 'see' those who have crossed over, standing before them as if they were 'alive' (as in their physical body). Spirit people can usually still see their loved ones regardless.

You're entitled to your opinion Jan.  Personally I don't believe that anyone can see 'those who have crossed over', I know you believe this, and that's fine - I doubt that many people are harmed by such a belief.

Where would beings of light/spirit/souls/ that which is really 'us' go to after physical death if there weren't any further places? If you want the sciencey bit - think on the lines of energy can neither be created or destroyed.

Well there was a time when both you and I didn't exist - before we were born.  Why should it not be just like that after we die?  If you want the real sciency bit, then there doesn't seem to be any good reason to propose that we should carry on after the energy that caused our brains to operate has dispersed. 

Not so much if we are aware that life carries on after physical death whilst we are here on Earth - and we are aware that our loved ones are still there.  Also memories of any other lifetimes we have had might be temporarily blocked to help spare us from pain.
 

How do you remember things when the structures that held those memories have been destroyed?  Think about alzheimers, or dementure, it is the brain that holds memories, tells us who we are and who we know.  Destroy that part of the brain that holds the memory of someone and the memory is gone.