Both of these requests are similar in the sense that they both involve parents asking others to monitor their children and be attentive to what they are doing. Polonius wants someone to watch over Ophelia, while Claudius and Gertrude want Rosencratz and Guildenstern to watch over Hamlet. Shakespeare wants to show how, even though both of these are requests of parents who want their child watched, the intention and consequences in each case are very different.
They cling on to the ghost of Christmas Present because of how man "want" many things around this time of year and they'll do anything to get what is needed. Hence, there are some people who will do "ignorant" things to get what they want.
I think it's this because the text says "until he saw fat Joe walk in through the rear door, then his courage began to ooze." meaning that his confidence left when he saw fat Joe walk through that door.
