Expert advice on Commercial Bank Loan Help.

Hey BP,

I just got approval for a 350k loan for 20 years ARM (5 yrs fix) from a local bank (Chelsea Groton Bank) Purchase Price for the deal is 550k

This is my first time getting a bank loan, what should i expect. What can i do to get the best deal. 

Can i negotiate the rate and terms on the loan from the bank? and how do the bank determine the closing cost?

BP please help and explain the system so i can understand more, so i can try to avoid any unnecessary mistake.

-Steve