Thank you F. Lee Bailey. Where'd you get your law degree, Walmart?:doh
Palin is a public figure who gets photographed all the time. A photojournalist would own the copywrite.
The similarity to the cover of Palin's book cover is the only issue. Palin's publisher could argue that a customer might pick up the dark cloud nightmare book by mistake. But even that's a stretch since many book covers looks similar and it is up to the customer to actually read the title of the book he/she plans to purchase.
In which case, the attorney for Palin's publisher could argue that people likely to purchase Palin's book are not too bright and a can't read above a 4th grade level.
If the essays are of the humorous variety, which is very likely because well... Palin is just so funny...in a scary way, then the book would be considered a parody or satire of Palin's book. Case closed, end of story.
Good luck with your BIG legal action...