My first suggestion would be to look on-line or buy a good book on the subject of rod-building (or both). I own Art Scheck's book on the subject and it has really helped me. The tutorials I have found on the internet for cork shaping have filled in the information that Art's otherwise great book omits (for the purpose of being a little too technical for the newcomer to rod-building). I suggest you do a search on the web and see what you come up with before you buy any materials.
Next, get a catalog from Angler's Workshop and other rod-building supply houses and have a thorough look through it to see what sorts of options exist. You will find that most of the things you're looking for are already in existence; the black guides and dark cork (which would be either rubberized cork or cork burl) can be readily purchased. While I used to split my orders for materials up between three or four suppliers, I now purchase most things for a project from two places, so though it pays to do your shopping around, it often makes sense to buy the bulk of the supplies in one place.
The XP is faster than the blanks you listed; in fact, it's quite a bit faster. For trout fishing in small to medium-sized streams, I suggest re-thinking the 6-weight and going for something lighter and shorter. I prefer fly rods in excess of 9-ft. myself, so I can understand your desire for something in the 10-ft. range, but having fished some streams of that size in the past year with my 10' 5-wt. T & T Horizon I can say that I would have been much more able to fish effectively with one of my 8' rods.
As for sanding the blank, I can see why you'd want to do it from the standpoint of saving some weight, but I believe that putting a high-end blank through the process of sanding it could potentially destroy it and would almost certainly void the manufacturer's warranty. If you must have the matte look, go for something like a Loomis IMX, which is quite fast and is very light.
Although you could certainly start with a high-end blank for the first project, I would suggest buying something inexpensive to practice on. My first rod was built on a Cabela's FT (which is also matte-finish) and I'm glad I went that route rather than through a "better" blank at first. Now, 7 or 8 rods later, I do work that's passable and every bit as good as what comes off the rack at a shop, and I feel totally comfortable building on $300+ blanks. I'm no where near as good a builder as someone like Bob Meiser, though!
Have a look at his website (he's a forum sponsor) to see some of his beautiful work.