Only time alumni might give you an edge is when you are a legacy( thats if someone in your immediate family graduated from those schools and is alumni) If no, than the endorsement of "family friend Harvard alumni" would be almost same as a good interview report which by the way is conducted by a regionally selected alumni. I doubt they will see huge difference between the two alumni, both from the same school, unless the "family friend alumni" has something serious and personal to tell.

Interviews for Harvard are required from all students but randomly selected in other schools you listed based on region. Interviews only can affect so much- it only reinforces and double checks whatever you put on your application and not much more. I had three interviews one with yale, another with columbia and upenn, and all of the interviewers stressed the fact that interview can not get you in the school. One important thing that it can do is to prompt the committee admit you if you are on the edge of either being rejected or accepted.

You said you "sent transcripts" to the alumni you want a recommendation from. Well, I have to tell you that if they dont have enough experience with you that they need to base something on your high school transcript, then nothing from them would be helpful. Even good teacher recommendations dont need a transcript. It is never good when a letter might be based on numbers, averages, GPA, scores and other things that you can not as an individual place human face to.

Oh, and about the teacher recommendations - How are you going to get them now that you have graduated from high school? Same about the counselor ones. I would call the admissions because I am not really sure what you should do in your specific case now that you’re out of school

If you have any questions you know where to find me.