Just buy a new water pump they are like $20. For the head gasket, depending on your mechanical background they can be easy, or hard. My first one took me almost a whole day, then half a day, now i can probably do it in like 2-3 hours. Just chock the timing chain or your life will suck.
Knowing if the water pump is dead can be as easy as trying to turn the pump by hand, to not knowing until you take it off. If you have a lot of miles on the car and the water pump looks just as old I would replace it anyway since it probably will need one sooner or later.