Don't hesitate to ask questions. THats why we're here.
If you don't delete version one of the route, it will still be there. CM2 will recognise each route as a completely seperate entity. It goes by KUID number, and has nothing to do with the route name. You can leave it there and it won't hurt anything, but it will occupy disc space on your hard drive. If disc space is at a premium, you can delete the old one thru CM2.
Once you have the new route DLed and installed it will appear in your Surveyor list of routes. It will NOT appear in the Driver list until you create a session for the route in Surveyor. If you've never created a session before, all you need to do is open the route in Surveyor, and just simply place a loco on the track somewhere, save it, and go to Driver.