You can ask your local wide format printer. Typically wide format printers feed paper up to 5' wide rolls. Your local Kinko's might be able to help. Speak to the manager and ask if he/she can get you that size paper, or ask if he/her can refer you to...
The best format to shoot in - provided your camera gives you the option - is RAW. That has been called a 'digital negative'. JPEG is a 'lossy' format which means that each time you open it you can loose some of the digital information. That does not ...
You must format the merge fields in the main document in Word to do this. Select the merge field and Right Click>Edit Field. This will bring up a dialog that will allow you to select the Category and Format. God Bless Frank Pytel