How to do research on people??

So I'm a student trying to get into IB and I've compiled some names to contact in order to network for my first intern gig.

And according to the networking guides and the general wisdom here and everywhere else, I'm supposed to research the people that I will be talking to?

Uhhh... IDK how to do that after the surface level (reading their linkedin bio and searching their name on insta/FB) 

How do you guys manage to find more info on these guys since it's very hard to find anything else other than schools/companies on linkedin, and when the insta posts are just them drinking beer?

Also, I've heard some ppl research their interviewers?? like how do you even find out who the fuck is gunna be interviewing you?? 

Can anyone please enlighten me?