One of the things i try to tell new juniors is to not worry about racing junior specific races that are large. They attract 1's and 2's. A local junior race or a cat 5 race is a better option for a junior who is new to racing.
You have to be careful with anything you leave around at a bike race, and remember when doing a feed make sure not to leave the bottle out for too long before your kid can get to it. Feed zones are basically every man for himself, and someone can and will take the bottle from you. If you only need 2 extra bottles, bring 5, trust me someone will take the extra bottle (Hell i do it all the time because i don't normally have a reliable feeder).