Our Open House programs in the fall are held on Saturdays so there is not an option to sit in on classes. Faculty will be available from the various academic departments to speak with students, and as well we will have a large number of current students available to answer questions. The October 20th Open House will feature the Natural Sciences and Engineering departments at Hopkins so your daughter will have the chance to see faculty from the Math and Chemistry Departments. Economics will not be on display as it will part of our October 27th Humanities and Social Science program.
Unfortunately as far as your second question, I have no idea what "SOPS" stands for. If it relates to some type of off-campus recruitment events, you may check our web site here:
http://apply.jhu.edu/visit/offcampus.html.