I have 3 questions about Abraham Lincolns assassination, why did the Lincolns notify Ford's Theatre?, John W. Booth made final arrangements. What were they?, Why did officials want to move Lincoln from Ford's?
The Lincolns were regulars at the Ford's Theater and notified James Ford, the owner, on April 14 that they would be attending "My American Cousin" that evening. The Lincolns were typically offered a special box over the stage. Since General Ulysses Grant and his wife were also supposed to be accompanying the Lincolns, two adjacent boxes were combined and upholstery touches were provided, including the rocking chair on which the President sat. The Lincolns must have notified Ford's theater so that these arrangements could be made.
John Booth made arrangements regarding his escape (a waiting horse outside Ford's theater, stored weapons and supplies at Surattsville, and a plan to cross the Potomac River). He succeeded in the first two, but was killed before he could cross the river.
The officers and doctors decided to move the wounded president into a better place, where treatment could take place. Since the White House was far away and a bumpy carriage ride would be dangerous, they decided to move him to Peterson House.
Mary Lincoln, Abraham Lincoln's wife, had notified the theatre that they would be attending the performance of Our American Cousin, in particular actress Laura Keene.
John W. Booth made arrangements with a livery stable owner for a getaway horse, and a clear escape route. He also told his companions of his plans, so they they each could assassinate different people and/or help him in the escape.
I am not sure what you mean by the last question, and I'm going to assume you are asking why the officer protecting Lincoln decided to leave at the night of his assassination. It was known that Lincoln was not huge about protection despite the frequent threats he received, which might suggest how the officials were not as committed perhaps.