Hi! Interesting question...thanks for posting.
So I usually tell applicants to not try to seek out connections with the Ad Com or other Administrators - as often times it's really hard to make a meaningful impression (they meet so many prospective applicants!) and it can be a big risk if you make a bad impression or come off as too pushy. But the fact that you already have connections is really good and I'll assume they're "warm" enough that you could ask for a phone call or meeting without that seeming awkward. If so, then I would definitely do so. I would go into those conversations with the intent of finding out more about the school, its culture, and what it seeks in applicants. This will pay off when it comes time for you to answer those important questions about mutual fit with the school. Also, some school's ask you to list students/alums you've spoken to on the application, so you could list their names there and that would look good.
I would advise that you don't ask them to put in a good word for you though. If they offer it, then great! But really just approach the conversation seeking to absorb knowledge about the school. So yes, I think it could help you but in a more indirect way.
As for other notable alums, I would say it depends on how "notable" they are (rooms/buildings named after them?

) and whether they have good contacts in Admissions or with other school representatives. If they're someone who's actively involved as an alumni leader or donor or alumni interviewer then they likely have someone they are in touch with frequently at the school and it would be more natural for them to put in a good word for you. I'd want to know more before they just submit an additional letter on your behalf. I can't speak for other schools, but I know Booth has a website where alums can informally recommend an applicant (
https://www.chicagobooth.edu/shapethecla ... mmend.aspx). So this might be a great option!
Good luck and keep us posted if we can help!