Uzi,
What you say is very true and humorous!

Make it easy on yourself! If most of these trivial things make no difference to you, then practice the phrase, "yes, dear, whatever you say"!!
I hear you with "cake shapes" and all. It seems so insignificant, but to some it is a big deal! But these are little "pains" that go with wedding planning, and one can go nuts trying for "perfection." I'd just leave it to her!
As far as her "extra steps" go, I think the fact that you realize and accept it (I assume), is all part of the "getting to know you" stage. And by your post, seeing the humor in it is a plus in developing a "good" relationship. Good luck to you!
Btw, I can also relate to the "blue car" story. My husband was into cars and was always buying/selling one for another. He really liked the 55 (or was it 56

) Chevy. He tried to explain to me in detail how I could tell one if I saw it. All I knew is I wanted something the right color, than ran good and looked halfway decent and I was happy!!
TIS