When I flashed the build from March, The SDcard got a wierd mount name, some random letters. I unchecked then mount name separation in the sueprsu app, so I could access the contents. The problem was still that titanium backup could not read it's backup settings. I could read my backups but the settings of which titaniumbackup backs up for itself could not be read. I revered to my previous Lolipop ROM and everything worked okay.
I have never used marshmallow before, so no idea if this is a general problem with sdcards or not.
About the suggested TWRP version: possibly. The latest version has better support for Android 8. JDCTeam does have an unofficial TWRP build for their Android 8.1 ROM, but with TWRP 3.2.1-0 released may no longer be necessary.
EDIT: I just realized I never actually answered your first question. If TWRP is packaged as a zip file, you should be able to simply reboot in recovery mode and install it using the existing version of TWRP. As you note however, your version of TWRP is newer. Replacing TWRP is no longer done through flashable zips: current versions of TWRP has an install routine for image files.
#include <std_disclaimer.h> /* * Your warranty is now void. * * We're not responsible for bricked devices, dead SD cards, * thermonuclear war, or you getting fired because the alarm app failed. Please * do some research if you have any concerns about features included in this ROM * before flashing it! YOU are choosing to make these modifications, and if * you point the finger at us for messing up your device, we will laugh at you. * */
Well, for my opinion I think that @AntaresOne is going to the wrong direction of his ROM developing career and should turn around at the right direction, I think that @AntaresOne have made a wrong choice about making cm13 and a closed chapter(I don't care about optimized), the only way to fix this is by making at least cm13 an open chapter again(or optimized, its @AntaresOne choice)
Sent from my GT-I9505 using Tapatalk