The wifi issue is typically a firmware issue not matching (from my experience of what I have seen posted on xda). Below is the firmware on my phone that was OTA and running. I am currently not having any issues with WIFI (now bluetooth with my car since update is a different story).
Oh also the red triangle is the delivered recovery. Try the fastboot boot trwp from the boot loader.
M8_UL PVT SHIP S-ON
Mar 1 2016, 00:59:13.24432
For others (not sure how everyone does this) - historically I have backed up my recovery partition and a non-rooted backup so that I can go back to stock anytime. Since Lollipop, I have actually not installed TWRP, but used the fastboot boot twrp.img method. This way I still have the stock recovery inplace but allows me to switch between stock ROM (don't install super su on restore) and ones off of XDA.