2 button suit vs. 3 button suit

Alright, I'll admit, I don't regularly wear a suit to work and I'm not very familiar with the details of how a high quality suit should be worn or constructed. That said, I'm currently in the process of buying my first bespoke suit. I got measured today by my tailor and he has way too many options for me to even think about. If there are any more fashion conscious individuals on the board, I would love to hear your input. I am deciding between the following options:

1) 2-button vs. 3-button suit. I am 5'11" and my tailor told me that I should stick with a 2-button. He mentioned that only people above 6'3" should have a 3-button suit, especially in Finance/Wall Street. I've always felt more comfortable with 3 button suits, but he was strongly discouraging me from getting a 3 button. His 2-button suits seem to place the buttons a little bit higher, similar to a Zegna or Canali. Which one is more appropriate for business school/interviewing purposes?

2) Navy vs. Charcoal solid. I'm almost dead set on Navy. I have a charcoal pinstriped suit already that is off-the-rack, and it is decent.

3) 2 Side Vents vs. 1 Center Vent. Now we're getting to the part where it is too granular for me to even distinguish or care between some features. What are the purposes of each and which looks better? My tailor recommended 2 side vents.

4) Stitching on the lapel. My tailor recommended that I get a subtle stitching on the front lapel, and mentioned that it looks classy. I've never seen this and was a little bit hesitant. Is this gaudy?