Re: how do I send a photo to another mobile phone
You can use Bluetooth, WiFi transfer, or just use email, or SMS.. Bluetooth is the easiest; WP announces itself automatically, you just need to pair it with the phone you're sending it too.
If you use the built in hotspot you can always use a WiFi direct app. The other person needs to be on the same network, and navigate to the website your app creates.
Your final option is the cloud. Use OneDrive, and then share it with them.