Search for older versions of apps that still support Android 4.3. Recommended repositories include: how to install working android apps on my passport?
Turn off your Passport. Hold Volume Down + Power for 10 seconds. The screen will go black. Connect to your PC. Using QFIL (Qualcomm Flash Image Loader), flash a modified unlock.mbn file. This is the most dangerous step. If the wrong file is loaded, your phone becomes a paperweight.
Android 4.4 is inefficient compared to BB10's power-sipping QNX. Expect 6 hours of screen-on time instead of 12. Install to hibernate background apps.