Finally, get involved in some impressive extra-curriculars outside work (it seems you have done this to a certain extent).
What would adcoms consider "impressive" extra-curriculars? I haven't yet graduated or secured a job, so of course I can't be certain, but I plan to get involved with a number of the things I wished I'd done in college. I hope to do some combination of: playing baseball, learning martial arts, playing drums, taking dance lessons, taking cooking classes. I understand that these don't offer the opportunity to display management skills as they are mostly personal, but would they impress an adcom?
I know for certain that I will be involved with philanthropy. It's very important to me as a religious/socially conscious person to do so. In this sense, I can show initiative and perhaps manage people to an extent. Are certain philanthropies viewed more favorably, or is it more important to show involvement, initiative, and leadership?
Would this increase my chance at admission to a Catholic university like Georgetown or Notre Dame?
I'm thinking 'impressive' probably means philanthropic involvements where you might have started or helped start a nonprofit organization, held an influential board position on a nonprofit, organized a large event, or maybe led a team towards a new initiative.
If you're getting involved in the community and making a difference by helping others, I think it matters very little whether that organization has a religious affiliation or not--even for Catholic universities.
It really is all about the actual experience though. For example, I'm working on applications right now and there is very little space to elaborate on your EC involvements in the application itself. So if you DO want to elaborate on them, you'll have to bring them up in your essays. And you have very limited space in your essays--so if you're going to lay out an EC experience there, it needs to be significant!