Some notes on what's going on. CM13 is on its way, I'll release it in a few weeks. I'll then stop AOSP 6 dev (well, it's already stopped since I'm working on CM13...).
OpenGapps seems to be quite unstable these days. I remember having a working tablet before updating OpenGapps and seeing all those FCs. Maybe you could try older versions.
As for houdini... I think there's very little hope
Last thing is exfat and f2fs support: TWRP3 will be released at the same time as CM13. They'll have the same exfat and (updated) f2fs code so no more sdcard working only in TWRP or CM and hopefully less f2fs bugs.