geoserver - What map source/API/tools are recommended to create Web GIS/Mapping application utilising Microsoft technologies?

I'm researching about technologies (around Microsoft tech) to create mapping application and would like to have advice/suggestions.

Brief requirement to build mapping application with Microsoft Platform:

1. Adding Pins on the map.


2. Clicking on the pins to get more information as popup.


3. There may be links connecting to various pins (i.e. shortest connection, and not actual physical representation of path on the map). In some near future there may be requirement to represent actual physical path between two pins.


4. Clicking on the link to get more information as popup.


5. Base maps can be hosted externally or internally.

Which base map source can a good candidate for any apparent reasons? (i.e. Google, Bing or OpenStreetMap).

Suggestions for API/Controls for creating web application using ASP.NET or Silverlight app or windows based WPF application.

How GeoServer or MapServer can be useful in for such applications?

Suggestions for other notable tools/API/controls for designing such applications