Snooker is the same in CPE, USDAA, and AAC; Ado's description is better than I could ever do. I think it's the most confusing game of all to learn, but it is absolutely my favorite now that I get it! The only difference is that in CPE I've never seen them require the use of all four reds. There are usually four on course, but you only need to use three. So it's RED, obstacle, RED, obstacle, RED, obstacle, closing.
Jackpot is basically the same as Gamblers in USDAA (and AAC, I assume). You have a minimum number of points for your level that you have to get. Each obstacle is assigned a different number of points (1 for single jumps, 3 for tunnels/tire, 5 for contacts/weaves I think). During the opening, you want to collect as many points as you can. You can do any obstacle twice. After a set amount of time (usually 30 seconds) a buzzer sounds, and you move on to the jackpot, which is a series of obstacles set at a distance that you have to perform without crossing a line. The distances for Level 1 are REALLY small. At my trial last weekend, the jackpot was a tunnel to two jumps, and the line was basically at the edge of the jump standards.