Hello,
I wouldn’t use Multi-site for this scenario. I think you are better off using the built in Categories functionality so you can have different categories for each topic.You can even have category items in your navigation so it makes it easy for your website visitors to find content easily.
In terms of monitoring the site I would use Google analytics to see where people are coming from and how they found your site. It is easier to administer a single wordpress installation than a multi site. Also some plugins don’t work well with multi site such as some backup plugins.
I hope this helped
