I'll give it a try...
1) Here is the link to the catalog of classes for both Florida and California. You can select which location and narrow the list. We are taking a class in October and my son will also be in 2nd grade. The classes are based on an age range, from age 5 to 18. But only certain classes are offered on certain days.
http://www.disneyyouth.com/individual-enrollment/catalog/
2) You can purchase tickets for 3 day to 8 day, basic tickets or hoppers or water park&hopper. You will make your choice and purchase when you register for the class. You will be able to purchase tickets for the child and the child's immediate family (parents & siblilngs). Be sure you enter all members of your family during the registration process and then only check-mark the child and adult that will attend the class. These tickets are non-refundable so be sure that your trip is definite before you purchase.
3) The YES tickets are approximately 40% off the Disney price. You can go through the registration process and the see the prices without actually making a purchase. Another common question, if you staying on-site, can you use a free-dining discount. The easy answer is no. You can use a room-only discount. The free-dining is possible, but takes some complex planning, and room-only is usually a better deal anyway.
Hope that helps. If you have more questions, post them and someone will try to help.