[Ray Carlton]

I have no doubt that you know what you are talking about in a strict sartorial sense, however this is overdone for a beginner in suits.

Braces:
Sure, get them if you like them. But this is clearly not necessary. Especially, braces should be avoided when there are bell loops on the pants, but no brace buttons. Most RTW suits come with bell loops....

I am considering to get brace buttons on my next MTM suit, so I am clearly not against it in general. But I feel like, you empathizes this point way too much for a starter.

Double Vent or Single Vent:
Your explanation of the history is correct. However double vent is just the way to go in a business environment nowadays. Double Vent jackets are more comfortable and allow a more tailored suit.

If a young guy asks me for a suit recommendation for a job interview, regardless whether the interview is for an IB job or any other office job, my recommendation is simple:

Get a made to measure suit.

The fit of a suit is everything. Most people wear ill-fitting suits, so you already make a huge difference with a MTM suit.

Get a white shirt. Get a tasteful, but business like tie and add a pocket square.

This is already shows more personality than 99% of people in the room.

Braces, double / single vent and so on. All nice details and worth to consider, when you get your second or third suit.

But for the moment, your number one criterium is fit.

Do also not forget the accessories. Get a dress watch. Keep your shoes clean. Those details count.

Ray