Hey there, Chris!
I'm going to preface this by stating that I am a total newbie here and have not been to any events, as I just finished my armor the other day.
As somebody fairly new to all this, I can confirm that you aren't alone in being overwhelmed! There's a lot more to the 501st than most people expect. You should certainly be excited too, though!
From what I understand, spotters are almost always needed at events. They help out all the people in costume, as well as many other important things! There is a spotter section here where you can likely find out more information and volunteer for specific events.
If you're interested in the costuming aspect and are ready to take the plunge and start building, you can find information about acceptable costumes and requirements here:
http://databank.501st.com/databank/Membership:JoinUsI'm sure a veteran member will have MUCH more insight than I do and hopefully they don't mind me chiming in before I've even been accepted!