Maintaining Sophomore year connections?

I’m a sophomore student at a target/semi-target, and I’ve been trying to network with Alumni to learn more about the industry. At first I was nervous, but now I feel comfortable talking to alumni. In the past month, I had phone calls with an EB analyst, BB associate, and a BB VP, and they went pretty well. How can I maintain these connections for the next year by the time I actually apply can ask them to to push my resume? Also, how helpful are these connections if they say they are not very involved in my schools recruiting process?