“My video for the mandolin is all in G, however the fiddle one has all the tunes in A. This becomes confusing at times. Should I try to learn all the songs for both instruments in mainly the key of G to be better prepared for the camp?”
Learning how to chord along on three chord songs in BOTH keys is a very meaningful and appropriate skill for you to work on. Both keys are frequently used in bluegrass jamming.
Also, in bluegrass there are so many different songs that might come up at a jam, the idea is not to “learn songs”, but to learn the skills to help you follow along on songs you’ve never played before. This is NOT the same as rote learning or reading music. It is a different set of skills. Working with my jamming videos will help you develop them.
“Also, I find it easy to do the two finger G, C, and D chords on the mandolin but the A chord as shown is pretty difficult. Do I need to be learning other than the two finder G, C, and D chords?”
2-finger chords will get you by, but you’ll be able to control your sound better once you get comfortable on the 4-finger ones. If you get started now, you’ll probably have it by November. It’s hard at first, and may seem impossible, but don’t give up. Change between the different chords and see how cleanly and fluently you can do it. Eventually, being able to make chord changes quickly *without looking* will get you where you want to be.