there were two families in front of me both had a pair of young children under 10 years old. I was surprised at how patient they were considering the wait. I just kept thinking if I had brought my 8 year old daughter she'd be constantly complaining about being bored and hot.
first come first serve. You have to stand in the queue. If you come with someone you can take turns queuing and one can sit down. That's what the people in front of me did.
5000 baht paid in cash. I was worried as my notes were a little old with the visage of the former king printed on them but they still accepted. They give you a ticket and you come back the next day between 2 and 4 pm to collect.
I found out they close the gate at 11 and process anyone left in there even after 11. So don't worry if you're in the queue and there are 16 people in front of you and it's 10.55am, as long as you're within the gates you'll be processed.