(sighs)...I buy em' books and buy em' books and all they do is look at the pictures...
I can understand you wanting one of the sweetest MXers built, you are SUPPOSED to...but that doesn't mean you are ready for one. Remember this: most of us on this site and the free riding world for that matter can't fully use the power that a modern 250MXer is putting out, let alone a novice starting out. No disrespect towards your initiative or ability to learn, but a 250 two stroke is NOT a good beginners bike...no way, no how. A 250 needs to be run hard, cleaned out so it doesn't load up/foul and has a very strong mid-range hit...the kind that if not pointed in the right direction or ready for it can really hurt you.
If you really want a good learner, get a KTM 200 to learn on. It will putt around all day long, starts very easy, has a light clutch pull and when you get skills enough to twist it for more than a few hundred feet, it will damn near run w/ any 250 out there.
As far as wrenching on the modern four-stokes, if you have to ask what the difference is between it and others, trust me on this, you don't need the hassle yet. Only tryin' to help :)