Yeah I'm the same! A huge UWP fan, I also have a windows phone as well and those apps just work seamlessly over to there (think I'm like some kind of 3% of the market or something so edgey!) so I'm all for a nice tight UWP app. As for Xamarin its a platform that allows you share code between apps on different platforms. So instead of having to do your UWP app again for iOS or Android (or whatever way its done), you can share the guts of your app between all of them and then just do your iOS, Android and UWP specific stuff. Its really neat!