Ok, so ... couple of immediate answers ...
Firstly, have a quick look at your previous thread222-1803165, in which I provided an example of how to use Bing Maps to calculate driving distance between two waypoints. The XML that is returned contains way more than just the total distance - amongst other things it contains a set of attributes called EntityAlongRoute, each entity representing a long/lat point on the route. Simply retrieve and plot those. Or you can modify the URL I provided in that example by adding routePath to the RouteAttributes parameter, which adds a RoutePath attribute to be returned that contains an optimised set of (long/lat) coordinates to the Bing response (same values as EntityAlongRoute, but EntityAlongRoute contains a bunch of other date you may not be interested in)
Second answer - seems to me that you are simply trying to replicate functionality that Bing Maps already has. So why not use the Bing Maps v8 map control that your Bing key gives you access to?
