NOR flash as USB Mass storage with a Cortex M MCU (For USB Data logger)

I have a 4MB NOR Flash. i want to show this memory as Mass storage on a PC when connected as a USB device.
I have some confusions regarding the need of Filesystems on a NOR flash. I have a reference device (a data logger which mounts its NOR FLASH as USB storage when connected to PC. It uses FAT as the file system).
What i am trying to do is create a File on the NOR flash with an MCU. and Mount this flash memory as a Mass storage device to a computer through an MCU. And to be able to copy the file from the PC.
So far what i have concluded is that i need an MCU with USB_OTG_FS support , a File system for the NOR flash , and a way to Generate a PDF file through the MCU.
1) Is Mass storage class is a good approach to access a file stored in the NOR flash ?
2) Do i need a File system Translational Layer on the MCU side ? or the PC will handle all by it self ?
3) Is anyone familiar with handling a PDF file with an MCU ? i know a little bit about editing the source of the pdf file but not much.

I just need some expert opinion on whether i am going in the right direction or not

Microchip have example code for connecting a pic chip as a USB drive. Might be worth having a look.

Mike.