I got Lumia Windows 10 phone. And I want to try to develop mobile app for those phone. I have many questions about options in this case:
You can deploy 8.0 (Silverlight), 8.1 (WinRT) and UWP apps to Windows 10 mobile. With Xamarin you also Build an UWP app, but which includes the shared UI that works on all platforms.
Yes, UWP is supported, but only up to Target Build 15063 (Creators Update), Fall Creators Update Build 16299 is not supported, because Phones don't get the creators update as PC (different branch with less features).
You can deploy the apps via Device Portal or double click it inside file management app on the phone. Since Windows 10 1511 sideloading is enabled by default.