I have been using it for three days and here's what I experienced according to issues you have:
1. I flashed bitgapps that didn't have keyboard included and gboard presented in ROM is working fine.
2. I had the same problem with dirac, but...
It's recommended to flash firmware package before new ROM (some ROM's cannot even be flashed if the firmware is too old), yes the procedure is straightworward after you update your firmware - wipe: data,system, dalvik, cache and vendor then flash ...
1.-You could try to resolve your GPS issues by flashing any rom you choose, I personaly haven't tried any PE because i don't like this much google apps preinstalled in my system but i have been using many roms like Havoc, POSP, StagOS, Syberia, RR...
in OrangeFox - chose Menu in bottom right corner >> Manage Partitions >> Data >> Format Data (keep in mind that you lose all your files, make a backup to external sdcard or pc if needed)