Checkboard - We dont have an ALT page on the 744, which we did! Sounds a bit like the FMS on the Airbus which I miss for the diversion planning.
warmkiter - You must fly to FAA ops with a dispatcher 'in control'.
Here in the UK/EU no ones watching the destination change!
Some good hints there ... Its a shame RTE2 needs to be activated to get fuel predictions, but then it assumes from PPOS.
I have used RTE2 to work out an accurate mileage and pro-rata one of our flight plan div's fuel/mileage ... I think thats probably the easiest solution, although as you say worth adding a wind/alttitude saftey factor.