Richard:
CRM when properly thought out and aheared to is one of the most important disiplines in flight safety.
Many years ago I flew for Mobil Oil and they had the best crew coordination I had seen to that point in time and I have used the lessons learned ever since.
For me there should be very slight difference between the Captain and the first officer except the Captain has final authority.
As far as flying goes I split it 50 / 50 period, including changing seats.
There is no restricions as to weather decisions or take off and landing conditions. The pilot flying that leg or sector will perform all flying duties for that leg. Generally speaking if the x/wind or weather minimums are to difficult for the first officer they then are by definition not doable for either pilot.
My basic beliefe is the first officer be brought to Captain standards in the shortest time possible as far as the actual flying skills are concerned.
Experience will then be the only limiting factor to Captancy.
One other very, important item. When I held chief pilot positions in large flight operations if personality clashes arose I would seperate the pilots involved as safety is compromized when two pilots resent each other..It is unavoidable in the real world of human nature, so we should make all effort to watch for and seperate such indivuals.
Another comment, I found the first officers to be invaluable when trying to determine if there was a crew problem that needed correcting, all I did was listen and very often the warning signs were there to see. ( It is amazing what fratrenizing with the crew will bring out in the right circumstances,,usually in a bar.)
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The hardest thing about flying is knowing when to say no.