Professional Windows Phone developer here.

Here are the tools/processes usually used in WP8 app development:

IDE: Visual Studio Language: C# or F# UI: XAML (WPF) and Visual Designer Deployment: Windows Phone simulator (really good) or Device Architecture: MVVM (Model-View-ViewModel) with Two-Binding

If you do it right, you should be able to reuse 80-90% of the code in a Windows 8 app. With Xamarin, you can reuse 50-75% of the code on iOS and Android (depends if the app is UI-heavy or not).

I worked with native iOS (Xcode and Objective-C), native Android (Eclipse/Android Studio and Java), and Windows Phone. Microsoft has, by far, the best tools which makes building a Windows Phone app quicker than doing the same on any of the other two platforms. iOS is the second-best, and Android is the worst. Xamarin makes things a little better.