I agree with what others have said. I think you will be much happier with a rip saw, be it japanese or western, than you would with a crosscut. I strggled mightily with a cross cut dozuki, until I got my Adria. The problem was not that it was a japanese saw, it was the fact that it was filed crosscut, and required about 4 times as may strokes to finish the cut, which resulted in a very ragged kerf. I too like the wheel type Lee Valley marking gauge.
The key is being able to saw to a line. A little practice here will save a lot of frustration down the line (no pun intended). Find a practice board, and make a series of parallel lines along the end, in the same orientation as you would for the various dovetail pins and tails. Mark your stop lines then just practice cutting to the waste side of the lines, stopping without going throuh your stop line. When you have worked your way all across the board, cut away the kerfs, and start again. Go as long as your interest holds. Evaluate your work, and see what you need to improve upon. If you do this a few times every day, within a few days you will note great improvement.
One little tip I discovered quite by accident. is that particulary when making an angled cut, I do better if I start the cut while looking only with my dominant eye, which for me is the left. When using both eyes, while I can see more clearly, I have a built in error in the angle, pulling slightly to the left, especially when cutting the tails. If I remember to close the right eye when starting the cut, the error goes away or is reduced significantly. If just the right eye is open, the error is even greater. Once the blade is started, i can open the other eye, as the path is set. If you are having trouble sawing straight, try experimenting in this manner, see if it helps. for me, it has saved a LOT of frustration.
There is another video by Frank Klause (SP?) who has a very different approach than Cosman, which might interest you. Try several different techniques and find the one which suits you best.
Dan