Sounds like a solid plan! Note that you can also get BlueIris apps on Android and ios for a fairly low cost - still need the server + BlueIris server software, but being able to roll over in bed and check the cams in the middle of the night on your phone or tablet is indispensably convenient.
Should be able to send to the service member’s unit at FPO or APO depending on if they’re in the army, navy, etc. This page https://www.usps.com/ship/apo-fpo-dpo.htm has more info.
You can absolutely receive mail and packages when deployed in the military, even during wartime. When I was in the USMC, getting mail while out in the field was a bit of a psychological life line.