I am also unsure how much control I will end up having/am even comfortable having but my hope is that some people will also be tired and I can at least follow them around. The standing in line bit is not fun but the main concern I have is actually fainting as I have a disorder that causes fainting if I stand for too long but I am thinking of contacting the park and asking if I could bring a small folding stool or even just something to lean on.Not sure of what control you have over the day, but my advice would be to find places to take breathers a couple of times in the day. You'll likely have a few people in the group who feel this is eating up coaster time, but walking round a quieter piece of park for 10 minutes can reset everything well. There's always a couple of places that are away from the crowds.
For queues, don't think too much on where you are in the queue, where you need to be, how long it's going to take, etc. These will all up your stress levels. Queues are also good times to work out where you're heading next. The worst place to work out where you are going next is in the middle of a path just after you got off a ride, where you will have people streaming past and members of the group start wondering off.
Finally, have earplugs handy in case you end up in a particular situation you need them (like the guy behind you in a queue have an obnoxiously loud voice and laugh). I wouldn't recommend using them for extended periods as it can make the whole place seem even more confusing. You're going to be walking in busy areas where having poor sound input will make things feel unpredictable and more frustrating.
I'm not such a fan of parks as I used to be, but that's because I have two younger kids who have a tendency to walk off the moment you stop to look at a map, so half my day is spent asking "where's x gone now?"
do you have any earplug brand you recommend or just any foam earplug?