I want to get the body level fields from 'prepare quote' record(create mode) and pass it to the similar fields in a custom Suitelet page . (i have a button(UE script-beforeload) in the 'prepare quote' record which opens that Suitelet page in separate window). Im stuck passing the values from the record to the suitlet page. please help me with your solutions. thank you in advance/

Perhaps you could have a client-script with the function that the button points towards. That function could gather values from the current record and build the url+parameters for the suitelet.