Yes you will need a landing page for each location with all of the pertinent info like address, phone, etc. Here’s a tip for that. Add as much local info as you can to these pages. If you sell BBQ’s link to some local meat markets. Provide useful resources on these pages and they will go a long way. Of course make sure that they are well optimized too. Pointing some links to these pages would also be good.

You can use UPS/PO boxes but don’t overdo it. Google will catch you and ban you. If you have 2-3 that should be fine. But you will also need local phone numbers to match. Phone numbers are being used as a large trust factor since they change far less often than addresses do these days. So get numbers and keep them!

Submit your new pages, and addresses, to Google local business center and be sure to use the exact URL of your internal location page for each location.

Hope that helps.