You are getting some good feedback about your needs.
I am a professor who is running Moodle on my own. I started by installing Moodle on a hosted server (costing under $100US per year) and now run it on a virtual dedicated server (costing around $400US per year.) I typically have 4 or 5 courses running at any one time, and around 50-100 students at any one time. I like to save data, so it was the size of my mySQL database that caused me to move to a virtual dedicated server. So I might be using Moodle in a similar environment as yours. I learned Moodle on my own, and have been extremely pleased with it. My University uses Blackboard. I think Moodle is much better, so I continue to use Moodle on my own, even though it takes some time to learn.
My moodle site is at www.rjerz.com/moodle. It does not allow guest access, but if you want to take a look at it, let me know and I can let you see some of my courses.
What I find interesting is the many ways in which people are using Moodle. I have found one way that works for me, but it is not the only way. If you start looking around (especially on Moodle.org), I think that you can find numerous example.