Undergrad Summer Recruiting Questions - Grades, Reaching Out and Standing Out

I was wondering how firms felt about excluding your CGPA on your resume when applying. I have a 3.2 - 3.3 (semi-target, Canada) and have been advised to exclude it from my resume during recruiting. I've been successful at landing summer internships by doing this, but not for front office finance roles (think F500 internships, govt, etc). I have also (unsuccessfully) gone through an interview process for a MM doing this.

But I'm curious as to what the smaller shops prefer when reaching out to them. I have a couple boutiques that I have networked with and am waiting to hear from, but would like to start cold emailing/calling others soon and I'm not sure if should do the following:

1) Include my GPA & Transcript when applying if the boutiques prefer applying through email (with no preferences on submission material listed)

2) Include my GPA/Transcript, Cover Letter, and Resume when cold emailing, or just the resume and a brief intro

The reason I'm interested in the above is because I've seen a ton of mixed reviews on WSO and from talking to guys in the industry/career center folk. My grades have been improving over time though and I have some solid experiences on my resume, unfortunately not entirely finance/banking related.

After getting dinged from my most recent interview process, I learned the following:

1) Technicals are mandatory, but you NEED to be poised/polished to the core to make it past the finals and seal the deal, especially when it comes to MDs. You need to walk, talk, and act as if you're ALREADY one of them in order to be taken seriously.

2) Your story and confidence matters more than anything.

3) If you slip up on the above two, your chances of closing fall through the cracks granted that you're one of 20 for 5 slots shortlisted from a 1000

So my last set of questions are:

1) What advice would you give an undergrad in terms of confirming to the streets' culture? How did you manage to transition from your informal roots in college to such a cutthroat type of environment when presenting yourself to senior staff?

2) How much of the streets' culture applies to boutiques? I'm assuming each firm has their own culture (some being less formal than others), but should one play it safe and assume the same amount of professionalism/poise when networking/presenting/interviewing with them?

I think one of the biggest challenges for me is highlighting my personality and story in a way that doesn't come off as informal, too humble, or laid back.

Apologies if the above questions are amateur - looking forward to any feedback!