Pick up location for Visa on Arrival

To whom it may concern,

My friend and I will go DA Nang on Dec 13 - 17 and would like to use your service to get our "visa on  arrival". Do you have a map or location instructions on the Da Nang airport as I could not find one from your web site. 

Besides, How many days beforehand we should send in our application. 

Thank yous so much.