The clowns, rather the gravediggers, talk like that because when they are talking Hamlet is not present. It is after one of the gravediggers has exited that Hamlet and Horatio enter.
In Scene 2, Horatio tells Hamlet that he has seen the ghost of Hamlet's father walking the battlements. Hamlet is much amazed and insists on accompanying Horatio to the battlements to keep watch. That's what they are doing in Scene 4.
The beginning plot of Hamlet ended in the last scene of Act 5.
Hamlet. See http://www.opensourceshakespeare.org/views/plays/play_view.php?WorkID=hamlet&Act=1&Scene=1&Scope=scene
The Ghost, in Hamlet, Act 1 Scene 5
The quotation is from Hamlet, Act II Scene 2 "Polonius: Though this be madness, yet there is method in't"
The clowns are just grave diggers (everyday civilian) who are digging Ophelia's grave at the time.
There are no publicly known songs that specifically go with each scene of Hamlet.
In Scene 2, Horatio tells Hamlet that he has seen the ghost of Hamlet's father walking the battlements. Hamlet is much amazed and insists on accompanying Horatio to the battlements to keep watch. That's what they are doing in Scene 4.
The beginning plot of Hamlet ended in the last scene of Act 5.
Horatio, in Act 1 scene 1. Hamlet doesn't see it until scene 4. It has to be this way because in scene 2 Horatio tells Hamlet that he has seen the Ghost.
Hamlet. See http://www.opensourceshakespeare.org/views/plays/play_view.php?WorkID=hamlet&Act=1&Scene=1&Scope=scene
midnight
Horatio plans to go meet Hamlet at Elsinore, which he does in Act 1 Scene 2. Horatio plans to meet Hamlet on the battlements, which he does in Act I Scene 4. Horatio plans to meet Hamlet at the play, and does in Act 3 Scene 2. Horatio has no plans to meet Hamlet in England.
Hamlet - questioning the meaning of life
The Ghost, in Hamlet, Act 1 Scene 5
The quotation is from Hamlet, Act II Scene 2 "Polonius: Though this be madness, yet there is method in't"
In the exposition of Act 1 Scene 5 in Hamlet, two characters speak: the ghost of King Hamlet and Prince Hamlet. The ghost reveals the circumstances of his death to Hamlet, setting the tone for the rest of the play.