My Question is how do I find all of those broken pieces without taking the engine apart!
Simple answer. You don't. Start at the thermostat housing. It'll have to come off. That's where most of it should be. Might as well replace the thermostat while you have it out. Then you need to looka t the circulating pump. That may be able to be checked without removing if you can feel the impeller blades by removing the hose connections. If not, that needs to come off too. Then you can check the inlets into the exhaust manifolds. If they're all clean, you're probably OK.
You don't ave to prime the system. The RWP will suck the water as soon as you start it. You do need to verify that it's sucking first by doiing the bucket test. Disconnect the raw water intake at the hull fitting or the oil cooler inlet and make up a hose extension that runs over the side gunnel to a 5 gallon bucket filled with water. If you start the engine it should suck the bucket dry in 15-30 seconds. If it doesn't, you still have blockage or the sysetm is sucking air instead of water and you need to find out where that issue is at. 15 or 30 seconds without water will not hurt anything at all.
Did you wreck the engine running like this? Possibly, but you really won't know until you get it cooling as it should be again. First things first.
