Answer to Question 1
If a boiler runs out of water it can explode as a result of steam pressure. A boiler that is extremely low of water can shut down or can implode as violently as if it exploded. Implosion comes from the rapid condensing of steam into water, creating a negative pressure in the boiler.
Answer to Question 2
If you try to reset the breaker and the fault has not been corrected, it will trip again. An over current condition can lead to equipment damage and even fire. Determine why the breaker tripped and correct the condition before resetting the breaker.