I actually bet Jerry is a great guy to work for and a great guy to play for. I even think he's probably genuinely well liked and respected (at least a businessman). You never hear former players say much about him because he treats them well and, I think, really cares about his players. Maybe too much....which we see when extends Ratliff, hangs onto a guy too long, etc.
I do think the "walking on eggshells" thing is telling though. I think Parcells probably made it pretty clear up front on that plane in Jersey what he would and would not be doing. I think Jerry just sort of had to grin and bear it to get the team back in contention and drum up support for his stadium. I mean, that is basically what he said in a drunken stupor.
And I do think they probably do a lot of things by consensus. And I think the guys who is most convincing or gets Jerry's ear last probably has the most influence on his decisions. However, he has no clue how to build a football team. That is apparent as time goes on and he switches coaches, schemes, players, etc. The team has no real identity.
You need some acrimony in a front office. In Holley's book (The War Room) he talked about how the GM and the higher level scouts would constantly grill and challenge the lower level scouts to be sure they got the best information from them.
And as far as Garrett.....of course Jerry wants him to succeed, he picked him. He desperately wants to be known as the guy that picked up this former Cowboys back up and molded him into a successful coach. I wouldn't be surprised if, after the season, he really felt that changing play callers was a good idea (and it is), but between now and then, Garrett worked on him a bit and he's changing his tune.