1. Yes

2. Yes. But learning is rarely required. Why do you think none of your 18 devices will have codes already? If you do indeed have to learn a device, you'll convert it to an upgrade and delete the learns.

3. There is no way to "send" any codes from IRScope to the Nevo. You simply note all the learned codes and enter them into RM manually. It's actually much simpler to learn directly on the Nevo, then all you have to do is press one button, and the upgrade file is created automatically (in most cases).

What devices do you expect you'll need to learn? I doubt there is any need to learn anything, especially not 18 devices.

BTW, the Nevo already has codes for thousands of devices, and RemoteCentral, Hifi-remote, etc. have codes for thousands more. You can add many more than 18. But you can only assign 18 to device buttons. You could have many more devices on the remote and mix commands from all of them if you wanted.