Panels Custom Context
Large parts of the question doesn't actually make sense to me, but...

If you want to pass an arbitrary part of the URL as a string to a View, just assign that variable part to a string in the argument settings, and then set that argument, %url_from_string, as the argument to the View.

The better solution though, would be to create a new context type called 'content type', because I don't think a context like that is available out of the box, and then assign the argument to that instead. That allows you to do validation of the incoming context and gracefully handle an argument that's not valid.

A third solution, though mostly a workaround, is to tell the View to pull it's arguments directly from the URL. This setting is available for all content pane displays under their argument settings.