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

Here is the kernel patch, which enables CD-rom drive emulation.
https://github.com/CyanogenMod/andro...14893212fb0526

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.
https://github.com/flar2/ElementalX-...2b4f704d57a25f

Regarding exfat support. I'm not sure if there is a license or patent issue.
https://github.com/flar2/ElementalX-...9b775/fs/exfat