I wanted to provide an update regarding my random reboots and not being able to write to SD card. I'm glad to report it had nothing to do with this ROM.
I actually have a corrupted 64GB Sandisk Microsd card, which cannot be formatted. Found many complaints online about this card and Samsung devices. I tried formatting the card in Linux, Windows - no avail. Kept getting "card is write protected" error.
I finally contacted Sandisk and they confirmed it's a known issue. Card has lifetime warranty so they are going to replace it.