Creating a Virtual Camera Messes the Position of the Main Camera

These are good questions and suggestions, thanks for posting.

The default behaviour is to follow the scene view, because it has a navigation interface that many people find easy to use. Set up your shot in the scene view, then create a vcam to lock it in. It's the simplest workflow. If instead you want to position a camera and then grab the settings from that, then it's one extra step, assuming the the new vcam isn't live (and is therefore not controlling the Camera):

It will follow the target if you assign one...



...and set the procedural algorithms (Body and Aim) for follow and lookat (e.g. Transposer and Composer). The virtual camera is a versatile tool that can do many things, depending on how you set it up. That's why there is a Cinemachine menu to help create some commonly used things. By default, when you just add the component, you will get a passive vcam (i.e. one that has no procedural behaviour) which will stay where you put it.

That's a good idea, and we are in fact looking at evolving the Unity Camera in that direction. It isn't a small job, as we have to be careful not to break existing projects.

Again, historical reasons get in the way and make this difficult. However, it does make sense and our intention is to make future versions of Cinemachine more in line with this idea.

 

Here is one way you can work, which might make things more comfortable for you.

First thing, make a passive CM vcam and give it higher than default priority. That becomes a proxy for your main camera. When you want to move the main camera, move this object instead and the main camera will track it exactly.

From now on, when you create new vcams, they will be at the default (lower) priority and so will not control the camera. You can then use the "Adopt Current Camera Settings" feature.

 

Yes! It is already on our todo list