Does anyone happen to know a more in depth tutorial, to create more advanced, maybe moog-like  sounds?
The free demo contains the first 22 (out of 199) lessons.
As an aside, I goofed around with Overtone while watching & coded some bits here https://github.com/rogerallen/syntorial
So, no, Moog-like is probably too advanced for such systems. But it seem like it can be easily employed to have some fun with all kinds of FM.
Emulating analog circuitry may not be required to get a passable model of the characteristics of an analog synthesizer. While your model may never get to sound exactly like a Minimoog, the filter for example can be modeled decently with a simple IIR design and even more accurately with a more involved models (the Moog model from cSound springs to mind: http://www.csounds.com/udo/displayOpcode.php?opcode_id=32). This is the topic of a lot of research, both independent and published.
Sonic Pi, by the author of Overtone, is much more approachable and a blast to play with: http://www.sonic-pi.net