Do colleges really track if you attended an open house, emails, admissions session, tours, etc?

Some colleges do all of that, some don’t do any of that.

Go to the CDS for colleges you are interested in and see if they consider “demonstrated interest”. If they do then they likely do many of the things you mentioned. This is especially true if the student’s stats are in the top quartile of accepted students. It helps them eliminate (deny/waitlist) applicants they feel are using the school as a safety.