Long time Brown alumna interviewer here… just my observation (which has been affirmed by dozens of classmates)-- Legacy doesn’t mean much unless it’s paired with something else the U wants. So your original concerto had its premier by the Cleveland Symphony orchestra? Being a legacy can tip you in. Grandpa is itching to endow a chair in Nanotechnology? Legacy can tip you in.
But don’t overestimate the value of legacy if you are a regular strong student with great grades, scores, and a bunch of EC’s.
Unless your GC is telling you that nobody with your profile has been rejected from Brown in the last ten years- in which case- ignore me.
Re: the others- if you really don’t have a preference, ED is clearly NOT for you. If getting in to Amherst means you’ll spend four years wondering if you could have gotten into Yale- then don’t do it. Apply regular decision and add some solid match and safety schools.
What is a T-30 private school? If you add up the boarding schools, the day schools, and the religious privates that all have a good relationship with the Adcom’s at Brown that totals MANY more than 30… This is a big country after all.