Good Question, but it's hard to give an good answer without knowing how different the segments are so I'll try my best.

I agree that you should try to have this under one umbrellas as much as possible. A good example of a company that I've seen do this is http://www.revzilla.com/ who is trying to target several different type of motorcycle riders. They divide the website into sections based off the type of bike people like to ride.

For your blog I would set up categories for the specific target markets so they can quickly find the content that they are interested in. Also you can set it up so the content can be emailed to the right segment based off of the category it is in.

Hope this helps!

I love looking for and finding online courses to take in my spare time!

Here are some of my favorite resources:

You can search and register for online classes at several different universities.
- https://www.edx.org/
- http://oedb.org/open/
- https://www.coursera.org/

This is an aggregator of different online learning sites where you can sign up for courses.
- http://courses.skilledup.com/courses

For business management you can actually purchase real Harvard Case studies. It is a great method of learning and won't cost you a ton of money.
- http://hbr.org/case-studies

Hope this helps & best of luck!