I'm a current MAR student at YDS, and I would say that YDS is usually fairly generous with financial aid. I would say around 80% in most cases. They offer ten full rides with stipends with each entering class (they accept around 150 students).
I think the community service aspects of your application will be pretty important, from what I've heard that is a pretty universal quality of a YDS applicant.
And I'm not sure on the grades situation, there is little talk here regarding undergraduate GPAs.
Hope this was helpful!
