The Evercore interview was quite technical. They are looking to only advance those candidates who have a solid understanding of finance and valuations. Know how to do a DCF and calculate the WACC at the very minimum. You may also need to understand beta calculations for their business, how an overstatement of depreciation (or gain/loss from the sale of an asset) will flow through the 3 financial statements, etc. Bottom line: preparation will take a great deal of time and energy, so don't approach it any other way. Even rejection from the interview process is a positive experience if you spent the time to prepare, because all other interviews will be disappointingly easy.