I was an Appleseed instructor for a few years in the early days.
I was a good program (may still be, I'm just not involved in it so I can't say what it's like today).
You can (used to be able to) go to the RWVA website and there are links to topics like "what to bring", "how to prepare your gear", "what to do before you get there", etc.
It helped me. Actually, for me, the 7 day RBC I went to a few months later helped me a lot more (as it should, more time, more one on one with instructors.) How much did it help? A couple years later I ran into one of my old college/work buddies. We were talking about Appleseed. When I told him it helped me become a better rifle shooter he looked at me funny and said, "Hm, don't see how." Sounds funny, but we'd shot/hunted/worked together for 5 years and he'd seen me shoot, a lot. I was one of those guys who got the assignments for taking/making the longer range/difficult shots, especially when I was in the Army.
Back to Appleseed experiences. Keep an open mind. Pay attention. You will be getting so much information, so fast, that you may not remember it all or be putting it into use during those two days. Many people go to more than one and find that what they learned (but may not be putting into use) in the first Appleseed comes back to them and blossoms in the second Appleseed. For example, after my first Appleseed I thought I understood NPOA (Natural Point Of Aim). Nope. Not even. During the RBC (Rifleman's Boot Camp) a few months later I found out what NPOA really was and how to put into use it to improve my shooting.
People sneer at the 25 meter training/events. They think it's easy. Only 25 meters? Well, several years back the percentage of attendees that shot a high enough score to get a rifleman's patch was 12 to 15%. So, if 30 people attend the Appleseed, only about 4 to 6 would shoot scores high enough to get the patch. Not so easy.
I used my M1A. Later, I set up a 10/22 to mimic the M1A/M1 Garand. Tech sights. GI sling swivels and GI web sling. Extended butt plate to make the length of pull fit my 6'3" body/arms better. Magazines with a lever on the back that contact/operate the 10/22 magazine release similar to the M1A magazine release. Never used it at an Appleseed, but I've loaned it out to others who used it.
Hey, it's fun (shooting is fun, right), you learn to shoot your rifle better and you get to spend a weekend with people who probably agree with you on a lot of things.
I've still got my 25 meter rifleman score targets from 2005/2006 out in the garage. Used to have them framed/posted on the wall in my office at work. Got some funny looks from people but management never told me to take them down. Might be different these days.
One more thing. It's not easy. The position shooting, as well as getting into/out of position can be tough on your body. Take some kind of pain medication that works for you. Start taking them (by the directions) after supper on Saturday. You'll know why when you get up the next morning, so take more (by the directions) Sunday morning and again Sunday afternoon/evening to help get you over that stiffness/soreness from doing stuff your body isn't used to. That RBC week the only way I could sleep at night was taking my Aleve pills twice a day (breakfast and before I went to bed.)
Good luck, it's fun.
Thought of one more thing - known distance is easier than the 25 meter "test." Why? Because you shoot at one target for each distance. Just one. In the 25 meter AQT you shoot at 1 target in stage 1, 2 targets in stage 2, 3 targets in stage 3 and 4 targets in stage 4. That makes it more difficult because you not only break your position to reload but you break your position to engage each "new" target. That take time and introduces possibility for errors in setting up that position. And (used to be anyway) the needed score for the patch is lower for the known distance version vs. the 25 meter version. If you know the fundamentals then all you have to do for the full distance version is know the sight adjustments needed for changing distance to the target and compensate for the wind, if there is any. Not trying to start anything (caliber war) but a .308/.30-06 is easier for me to shoot at distance than a .223. If the wind is steady it's not so bad. Catch a day with the wind speed/direction is variable and the .30 caliber is more forgiving.