Making a book cake for a birthday

Hi,
I’ve never used fondant before and have a few questions…I’ve been asked to make a cake for a workmates daughters birthday who is a book lover. She wants a closed book, with black fondant, a book title written on the side , and just happy birthday on the top.
When using fondant do I need to put buttercream/icing underneath?
What is the best way to attach fondant letters?
What is the best storage?
The birthday party is Saturday night. I have to deliver the cake Friday as I’m going away. Should it go in the fridge, or just stay out?
If it was you, would you make and decorate the whole thing including the fondant and then freeze it? Tell her to defrost it in the fridge Saturday..OR
Make it more at the last minute on Thursday, decorate Friday?