Marketing sign tracking

Marketing sign tracking app. Would prefer it work for both apple and android devices. I'm not concerned with the overall look and freelancer would have much creative freedom. I need the app to track signs using GPS from my street team's mobile devices. Absolute must have's: -Employee takes photo when sign is placed, that photo then becomes pinpointed on map. Map shows nearby signs. -Distance from other signs must be greater than X miles (Example: if sign is placed less than 5 miles from another sign then error message occurs) unless sign is greater than X weeks old. (Example:If sign is greater than 2 weeks old then pinpoint on map changes color and new sign is allowed closer than 5 miles. Map showing pin points shows signs less than 2 weeks old with green pinpoint and older signs are red pinpoint) -Inventory tracking (Example: John starts with 100 signs and inventory drops by 1 value each time sign is placed. Alert is sent to admin when value drops below X) -Information must be downloadable -Admin user has complete control to add new users -Please respond to this with answer of 4+4 so that I know you are reading guidelines.