Hamlet questions

[detonator]

While reading Hamlet, I had some questions in parts of book.

Act I Scene I
Why was there a 24hr guard posted at the Danish Castle?
(was it because they were watching for the ghost who looked like King Hamlet?)

Act I Scene II

What does Hamlet think about his Father and Mothers relationship together?

Horatio thinks the ghost will talk to him over everyone else?
(is that correct? I believe thats what he thinks)

Act I Scene III
What advice does Lartes give to Ophelia?
(doesn't he tell her to break up with him and not to get married to him and dont have kids with him?)

What advice does Polonius give to Ophelia?
(doesn't he want her to stay with Hamlet?)

Act I Scene IV
What does Hamlet think of the Danish people partying?

Act I Scene V
What does the ghost mean by he must live in fire? When does he get out of the fire?

What request does the ghost make of Hamlet?

I really appreciate help on these questions, other than that i understand everything else from Act I. Please help me on these questions, Thanks.