It would be nice if you could add "DriveDroid" support in the kernel.

Here is the kernel patch, which enables CD-rom drive emulation.

And "USB Fast Charge" would be nice as well. It allows to charge faster when connected to a PC via USB.
Here is a example from the ElementalX Kernel. But they are using a install script in which you can enable this features.

Regarding exfat support. I'm not sure if there is a license or patent issue.