how do I disable and enable engine gimbal with activation group

Yeah I'm trying to figure out why you would want it to NOT gimble. I assume the example bellow makes use of the tinker panel and probably still has the added weight of gimbles even when not gimbling. So what would be the advantage?

It depends on what you're wanting to do it for. Do you have a use case that you can provide for toggling the gimbal? I quickly put this together, hopefully it can help you with what you're trying to do.

Try toggling heading lock for a similar effect.

I don't believe you can. Unless they added it in a recent update