There's a lot of wisdom in
this thread. It would be worth your while to read through it. If any more questions come to mind, ask them.
I would suggest that you:
1. be prepared for the unexpected. That would include being prepared for emergencies such as medical, financial, family. The more organized your team is, the better the experience will be. The Championships can be overwhelming for first time attendees and the organization will help keep that in control.
2. have a meeting place and run a buddy system. That way, no one is running around alone and everyone knows when and where to meet up. (Because the pits and the stands/fields are so far apart - the team is separated. That takes extra thought as far as coordinating arrivals/departures, etc.)
3. attend the
Championship conferences. This is the time of the season when teams have the opportunity to listen to and meet members of other teams that are so valued in the FRC/FIRST community.
4. make sure that you keep up with the Championship schedules/information. An example is the Thursday qualifying rounds that are being introduced this year.
I don't think it matters how many team members go. If everyone can go, that's great. Just make sure you can handle that. If only a few can go, make arrangements to keep a travel log or blog or video to share with the rest of the team. Take lots of pictures - and not just of all the robots, but of everything. That's where memories can be stored.
Have a great time!
Jane