Scenario creation

I have used the world editor to build a custom course through the Port, video of it in action here.

I have a few questions:

1) How do I save this without it over-writing the original Port layout? I've saved as a different name in a new folder, but whenever I load the port now this layout shows up

2) How do I set this up as a scenario or time-trial, including all the new assets?

3) How can I add shapes from other levels? There were a few signs I would liked to have added to act as tips for some of the jumps but none of them have textures.

4) Once I have a scenario set up, how would I go about allowing players to select their own vehicle, or would creating a time trial be easier for this?

Thanks all ^_^

 

There could be some answers in this tutorial series:
https://www.beamng.com/threads/highly-recommended-modding-tutorial-series.55534/