Hey supraman,
Here's the prompt from AADSAS:
Your Personal Statement should address why you desire to pursue a dental education and how a dental degree contributes to your personal and professional goals.
You are encouraged to compose your statement in a text-only word processor (e.g., Notepad), review your statement for errors, then cut and paste the final version into the text box above. Click the Save button and return to the Personal Statement to review the formatting of your text. You are limited to approximately 1 page (4500 characters, including spaces)
In response to number 3... 53 of the 56 dental schools are covered by this personal statement in your primary apps. The Texas schools, I believe, are the ones that aren't. Some schools (e.g UCLA, UCSF, Arizona, as far as my own experiences are concerned) will ask you for additional mini-essays on their secondaries.