Any actor who is being honest will admit there's always a small or large part of the real you in every character. It's impossible not to have that.
As for the stage fright, it never goes away. When I'm waiting in the wings to go on, it's agony every single time but I stay focused and I know that once I'm on stage it'll be fine; I'll be in my happy little bubble.
There are roles that are terrifying because they're large or you may feel that they're out of your line, but I'm never terrified once the actual work begins. Once you begin rehearsal, then it's small building blocks. It's solving little problems one at a time.