dont know about the thermostat replacement but the flush is pretty straight forward drain the old flush and refill it is better to use one of those chemical flushers they work a lot better than just running water through it. the coolant you replace it with afterward is not really important of what kind(autozone or a name brand) but what i would go with woud be the Dex-cool version of coolant you can tell it from the other beacuse it is orange it lasts a lot longer than the green coolant. hope that helps

98.5 Black SE ATX S&B filter, SVT MAF, optimized SVT TB, mesh grille, removed orange reflectors, painted rear reflector, gutted pre-cats, optimized SVT LIM, 19lb injectors, resonator removed cant afford an svt but lookin for 1 in nc