You can be a great role model for these kids.  This is a wonderful opportunity for you and them. 
 
Suggestions -
 Try to know the material.  Take a few days to go over the tutorials in the programming section; they are awesome!  The more you know the more your team will know.

Take time to work on a group activity every meeting.  Look up instant challenges -
http://wilderdom.com/games/TeamBuildingExercisesWebsites.html
  This pays off when your team is having trouble with one another;  Being friends and knowing they can rely on their partners helps make your job easier.  You can even point to concrete moments when you saw them working out a difficult challenge together and overcoming it.  Remind them they can do that now as well. This is also one of the three areas they will be judges on, so working on challenges is good practice.

Ask questions here when you have them.  You won't always get the answer, but you'll always get support!

Fund raising- car washes really helped us and allowed the kids to feel like they were supporting and creating the funding.  ( go to lush, well off area Gas stations to stage your car wash.  This will pay off in dividends, even if you have to drive a little while to get there.)  Corporate support is great, but we found it hard to come.   The best shot is often getting their parents (if they can ) to bring the letter of sponsorship to their work place.  Have several different levels of sponsorship- a Bronze, Silver, Gold and Platinum.  That way anyone can give on many different levels. I'll attach ours as a sample, but you can find many other letters on a google search.

Let the kids make most of the choices, even if you don't think they are the best ones.  Our skit was created by the kids.  I didn't always think they choose the best lines to say out of the options they were considering, but I let them do it (assuming the choices are between two appropriate things to say/do, etc.).  They really owned the skit and, in the end, our team won first place for their research and skit.

Hold kids accountable.  Decide what was in their control and what wasn't, but hold them accountable for what is.  Back to the skit example, one of our kids wasn't pulling their weight.  I made them do research during the time they wanted to be playing with the robot.  They never missed homework again.  It won't be that easy with all kids but hold them accountable to the work they need to turn in.  It will will make the whole team better.

Praise often, and always say something you like when you suggest improvements.

Before the tournament, get your kids to go over how they contributed and tell something they liked that one of their teammates did.  (That thing can't be repeated by anyone else.)  Go over who did what- the judges WILL ask them.

The handbook is great, but it's like a secret list only you know. Print it up a schedule and give it to the kids allowing them to make some of the scheduling decisions, that way they can check their own progress and see when they need to move faster and when they can spend time working on different ideas.  Even if they find they are missing their deadlines, it is something to consider- where we too unrealistic in what we could accomplish?  Do we need to scale back? What are our priorities if we need to cut?  These are really valuable life lessons.  Having the goal list was crucial to my first year team.

Mostly, I found the first year to be a learning experience.  Sure I wish I knew then what I know now (that leader guide book was spot on!), but you'll get there, and as long as the focus isn't winning, your team will have a great time too.
Good luck!
Brandy