I really have no freaking clue how to effect depth or height, for that matter. Your 'left here' and 'right there' comments are easy to explain and match the pan settings, but height? No clue. Maybe it's tied to the pan settings. For instance, in terms of pan settings in my DAW I noticed that the lead vocal is panned less than the acoustic. I basically closed my eyes and listened as I moved things left and right, stopping when I felt they were balanced and where I wanted them, not just a number on the DAW. That was on my IEMs. When I played it in my living room (after I sent a copy to Amie and Ian) that balance was different - and also reversed! Left was right and right was left. No clue what happened there.
The guitar you mentioned that pops in and out is the second track of the Electric Guitar coming from a different mic placement on the amp and I panned it just off center and the opposite direction of the other EG track. It's sonically just different enough in certain phrases that you hear it as a different instrument in a different spot.
I'll have to take a closer listen to the individual tracks again, but I'm pretty sure the hum you hear is the guitar amp. If I can pull it out without effecting the tone of the guitar, I will.