focusing problem and how to process possible simutanious input?

I am going to develop a testing system: when user scanned the badge, the bar code scanner will return a string (ended with a carriage return). Also, user can type in the badge number using keyboard and press "Enter" key. My questions are:
1. How to put focus of the returned string from bar code scanner to my text box area on the page? (focusing problem)
2. Is there a simple way to implement: whenever there is a "return" action, system will begin processing? i.e. either when the user scanned the badge successfully(so the bar code reader will return a string ended with "enter"), or user typed in the number and press "enter" key, system will automatically go to the next step and process the input number in the text box area?  

Thanks a lot!

-Scott