whom you cold email to, and CV?

is... is english your first language?

no reason.

how long did you spend deciding whether its who or whom

Typically analysts or associates at a firm/group until you work your way up to the senior bankers. Don’t reach out to senior bankers cold unless you know them/have talked to a lot of junior bankers in their group/have done extensive research on their group with meaningful questions to ask. School alums in those analyst/associate positions should help the email flow more smoothly. I typically always include a resume, just because they’ll always ask for it before talking to you on the phone anyways and if they wanted to pass it along to HR, all the better. Just say a simple “please find my resume attached” and don’t make a huge deal out of it.