1. Scale length. I believe the RGD I played today was a 26.5" length. I didn't even notice it at the time but it felt fine. Is it important to have a longer scale 7 string?
Not at all. It's recommended if you want a really low tuning, because of the increased tension. I play standard tuning in my UV7BK, which has a 25.5" scale, and it's perfect.