to get Juliet because she is only in a coma, she only looks dead
Juliet refused to go.
Balthazar is unable to enter the tomb with the Friar because he is not allowed to accompany him due to religious beliefs or customs, or because the rules of the tomb or site do not permit animals. Additionally, the tomb may be too confined or dangerous for an animal to enter.
He had to leave, for the "police" was on their way. He had no choice but to go...
romeo
The friar motivation to go to the monument is stop romeo from killing himself. The friar knows that the message he sent to romero, romeo did not get it which the friar know that romero would do something stupid like killing himself.
Because he heared the noises from outside of the tomb.
Friar Laurence tells the watchman that he is hurrying to get to the Capulet tomb to prevent Juliet from waking up and discovering that Romeo is dead. He instructs the watchman to go and fetch the prince and bring him to the tomb.
To break into Capulet's tomb
Love.
The Friar goes to Juliet's tomb to retrieve her, after being informed that Romeo never got the letter telling him to fetch Juliet. He planned on getting her out, and letting her stay with him until he could write another letter to Romeo telling him to come get her. As you probably found out, that didn't happen as planned.
Because he knows Juliet is about to wake up and Romeo will not be there, since Friar John was not able to deliver his message.
Friar Lawrence requests a crowbar to open Juliet's tomb and a letter to write to Romeo explaining the situation with Juliet.