The deal with the longer screws and the liner (they do make an extra thick ice tire now that doesn't need a liner) is that the tires don't spit out the screws when they're anchored deep, but beyond that, deep set screws don't bend over when they come into contact with the ice with the power on. They hit flush and you get the best bite. But hey, start with a knobby and shallow set screws to play with. You'll have a ball.
Maybe everyone knows this, but ice is a lot like dirt track, except it's a lot easier and a great place to learn how to slide. Blast down the straight and get a good head of steam, then just before you enter the corner, slide up as far as you can, hang your left leg out, and twist the bike sideways and down. The goal here is to have BOTH wheels going sideways to scrub off speed. Until you do this, you're missing the whole thing. Let it slow down until it wants to straighten itself, that is until you begin to get some bite and the bike wants to head into the corner. Now give it enough gas to keep it turning around the corner as you steer with the rear wheel. As you get 3/4 of the way through the corner, pick your left leg and put it on the peg (while you're still steering with the gas), wick it up and slide back to weight the rear wheel, blast the straight and do it again, and again, and again, ad infinitum. With a 4 stroke, there's usually enough engine braking compression to step the rear wheel out, with a 2 stroke, a brake or compression release is required to set the attitude of the bike.
Have fun! BTW, I've got to get the top end done on my CR before I do anything, but I doubt I'll race this year as my wife is getting set to "freshen" any day now and I'll be hanging with my little guy, Cole. I do hope to get some laps in our lake, though. Look for me next year.