Where do the historical accuracies end and fiction begin in Abraham Lincoln: Vampire Hunter?

There are innumerable fictions in Abraham Lincoln: Vampire Hunter (based on Seth Graeme Smith's 2010 novel). From the existence of vampires, to the mass collection of silver to combat the Confederacy's employment of vampires in their army, most of the film deviates from real life.

But where do the historical accuracies end and the fiction begin?

For instance:

• Did Lincoln's mother die when he was young?


• Was his former employer a trusted aide along his side all the way to the White House?


• Was Lincoln life-long friends with an African-American who also remained at his side throughout his life?


• Did Lincoln steal Mary Todd away from Stephen Douglas?