iirc coolant >should< be changed at 30k intervals. have you been checking the SCA's regularly? go to fleet.ford.com and poke around for owners manuals if you need them.
regardless- flushing done right should not damage the water pump. member fordforgotton has a good writeup on the procedure.
Green to Gold Coolant Conversion
i would ignore the green to gold conversion bits. green vs. gold is a hotly discussed topic. do it if you want, but consider yourself warned.
serpentine belt- my experience is that if you change the belt and tensioner, don't do the pump, the pump will fail soon thereafter. do you have any coolant weeping out of the pump drain hole? how are you rad hoses?
consider at least changing the thermo gasket and getting new thermo housing. you might be better off changing the thermo too. carefull on the housing bolts. they often are siezed in the aluminum housing. i could not seal mine up without any gasket goo.
poke about in the archives and use the search function for more users experiences.
dp