I vote for How to Write a Personal Statement: Story Basics. I think including general examples on what to do/avoid along with specific writing samples/essays would further strengthen the lesson. Thank you.
Your shots are not insignificant. I would probably say just under a 50/50. It depends on your major, your school, and whether you tell a compelling story in all of your essays, especially that Y250.
With your stats and URM status, I think it would be a mistake to ED. I wouldn't rule out HYS or others in the T14 with $$$. Just make sure you have superb essays and LOR.