Congrats Hardestadt!
Sorry to hear about the ding, rjacobs, liubhs, YihWei, and Smokedpotatoes.

For W/L, definitely set up your interview between now and R3 deadline (end of April) so you can be considered after R3 deadlines come out. Strengthen your application using the methods in your W/L letter as much as possible, and indicate your interest to stay on the list. You could possibly retake the GMAT, but try to do it early April so you can send your scores in.
Best times to visit campus are M-Th. I would recommend a morning class, lunch with students, infosession, and an interview, or interview, lunch with students, infosession, and a class. Contact club leaders for clubs you're interested in. Update your job status if there are changes, take a class in quant if your GPA is low, add 1-2 recommendations, etc... I think those are all great ways to show interest.
Let me know if you're coming on campus. Maybe I can meet with you if my schedule allows (Wed-Thur are better for me).
Good luck!