Been following this thread for awhile now. At this point, before you go and assume that it's an intake/head gasket which it might very well be, I'd make a small investment in the leak "dye" that was mentioned in one of the previous posts. This should identify any and all leaks that you may have which from looking at the pictures you provided, all the cooling system components look like they are past their prime.
Options:
1. Replace all cooling components including upper, lower, and heater core hoses. Replace thermostat and gasket. Then GET DYE to test.
2. Find and fix the current leak and address other cooling issues as they arise. Then GET DYE to test.
Either option requires DYE.
As to your question about how hard it is to do an intake gasket, that depends on your experience and patience. It doesn't really require any special tools or knowledge. A typical "shade tree" mechanic can accomplish it in about 8 hours or less using the basic assortment of tools like sockets, wrenches, screwdrivers and my favorite, a cool beverage. There are a number of components that have to be gently removed so as not to damage other components. Search this site and you will find a number of threads with pictures on how to do this. My guess is that you'll get charged at least $300.00 for a job that requires only about $20.00 in parts.
As to your question about water pumps, typical water pump failure is the pump bearing. Over time the bearing wears out and you can get a small leak out a weep hole near the bottom of the pump. When the bearing is really bad, you can feel and see the play in the fan by wiggling the fan and it will make a "metal scraping on metal" sound. The other component that wears out is the impeller inside the pump. The blades become worn and don't push as much water as they should and that usually causes a rise in coolant temperature resulting in an overheat condition.
Having said all this, GET THAT DYE!!
Hope this helps.........
