Audio editing help needed

There is a way to do it, even in free Audacity. It's called Auto Ducking, and it's one of the FX plugins that comes with Audacity. It's been quite some time since I've used Audacity, having switched to Reaper a long time ago, but this works pretty well. Essentially you set a threshold that specifies when to duck one track while another one comes in, and you can also specify how long it takes to gradually lower the volume and then raise it again, and by how much you reduce the volume. If you google Auto Ducking Audacity you'll certainly find some tutorial. I've used it before and it's very helpful. You just need to make sure you have your tracks laid out in the right order. I do a whole lot of sound design and audio editing and shortcuts like this are standard protocol that saves hours of editing.

I should mention also that Audacity does allow for some automation of volume and panning using envelopes. Essentially you set a point on your track, then a slope specifying how high or low you want the volume to raise, and how gradually, and then you put another point. Continuing this allows you to have the track's volume raise and lower at pe-determined points. Only thing is, the base envelope tool is not accessible in Audacity as far as I know. There is however a plug-in you can get that will work. I can't remember what it's called, but if you look up audacity envelope accessibility you should find it.