It certainly is! Because the Real Open Golf Tournament is divided into handicap-based categories, you will be competing on equal terms with scratch players.
No - to be eligible for entry, your scores must come from qualifying competitions at your home club or your nominated secondary club. Scores which cannot be verified will be removed from the leaderboard.
You should enter as a Junior. You will be upgraded to Adult membership (at no extra cost) when you reach 18, and you will compete in one of the Adult categories.