I am creating a Xamarin project, and I made it working with Android and iOS, but I can't figure out how to start the Windows Phone 8.1 emulator.
Windows Phone 8.1 is created as a project just like the other platforms.
I am running Visual Studio 2015 Community and Xamarin Business.
EDIT
I made it running by setting it as startup project, but are there others way by e.g. changing the project (where you choose if it is debug or release)?
I also want to know, how I can create the application to Windows store
To create app package go to Project->Store->Create App Package - It will open wizard for creating app package that You are able to send to store (reference: https://msdn.microsoft.com/en-us/library/hh975357.aspx)
In Visual Studio 2015 You can choose in taskbar: debug/release, CPU architecture, startup project and where to deploy an app - eg. emulator or device