Greetings and advice needed

I am new to the forum, and new to android app development. I have a long history of Windows based development in C#, including some Windows Phone. I have two areas where I need some advice.

1. Looking for a good android device to use for development. Not planning on this as my primary device and for my purposes could get by with just wireless access for testing. Have no idea where to start. Is there a specific OS version I should be interested in? I use AT/T for my provider and wonder if I should get an "unlocked phone".
2. C# development. Have downloaded but not yet used Code42 for Visual Studio. Would prefer to say in VS as all the other dev I do is in that platform. Open to learning Java, just don't want to go there unless I can't get what I want accomplished with C#. Know about mono and AndroidStudio, all suggestions are welcome.

Thanks.