Moog difficulty,
Well theres nothing to get used to..tweak knobs push keys. The principles of analog synthesis though has what I think is an excruciating learning curve. If you have ever spent any time on a softsynth like Arturia MiniMoog or the Modular then it will help you. I cut my teeth (still cutting) on the MicroMoog, and honestly (and crudely), Ive spent many many many many hours on the toilet with the MicroMoog Manual. 
Basically, just like any complicated technique on an instrument youll make progress in months and years. Like eastern Philosophy, you can go back and read the same lines you have read before and understand it on a different level.
THere are a lot of resources out there for people with vintage moogs and I would really sit down and try to find any of those old manuals written by Tom Rhea (friend of Bob’s and co-engineer). Those old manuals can be a real headache to grasp but (in my opinion) are loaded with a lot more technical information than some of the modern Moog manuals and written in a way that as your understanding increases you will get more out of them. I would find the old Minimoog or the Olf MicroMoog manual for some of the basics about analogue synthesis, as well as reading the current manuals over and over again.
Im not trying to make it sound difficult, but its essentially physics. THe MicroMoog manual has a synth tutorial and many sound patches and that helped me, so if you read the voyager manual or the Fooger manuals and they tell you about a patch then get patchcords and do the patches. Really, getting used to this type of synthesis involves not only reading, but practice.
I would strongly reccomend the DVD’s because they give you a grande entry level discussion. Advanced synthesis techniques are like Jazz because you will always learn something.
Most importantly, just have fun, be patient. Its really not all that hard once you understand WHY everything does what it does. SOmetimes I think I know exactly how something is and I try to help someone out and then someone comes along and makes me realize that I was thinking about it the wrong way. THats what this forum is for.
go to moogarchives.com, click on instruments, then modules, nd read the technical information contained there. The functional description as well as the musical description will definately give you enough stuff to read and absorb to last you a long time. In my opinion…all roads lead to modulars.
There are a lot more people on this forum who know so much more than I do about synthesis so just lurk, ask questions and don’t be afraid to make connections…no pun intended. HOpe you got plenty of patchcords!
Eric
I like the Roland KC series they are really powerful for their size. Its a matter of preferance and whether or not you are trying to gig as to what your requirements are.
Foogers I can’t live without…
Well I thought I woudl regret buying the freqbox at first, I also though Id regret getting the delay after I got it. You know what…I can’t live without either of those. THe Freqbox I think (serving as an extra oscillator) is choise. Its all just a matter of opinion. WHen I first saw the Fooger line I didn’t think I would ever want one at all. THen the more that I learned about them the more that I realized how beneficial they are. I really can’t reccomend one though I think that if i had them all I couldn’t live without them.
I’ve only gone through some of the presets and I’m already super impressed!! 
