I had the exact same issue as your problem One when I ran Oxygen 2.3.2. Although not for the first few months. I have also had problems with accessing sd cards. I have seen theories that a faulty sd card might trigger the black screen issue but I don't kow why that would be so.
I have since changed my sd card & have tried several other ROMs & the issue has not returned with any of the. It may have been the SD or the ROM, I don't know which.
As for problem 2 try installing yet another ROM. I can vouch for dGB working flawlessly on my phone but currently running Redux2 for 24 hours again with no issues.