Problem 1.
Firmware doesn't work with latest Arduino IDE and version 1.5.5 needed. The "fix" for this can be implemented in less than 15 minutes by replacing variable types. I've done it and was able to update FW using Arduino 1.8.x, why can't you release this easy fix?
Problem 2.
I recently upgraded Rev D printer to V4 hotend. Because mine uses older "silver" stepper I had to use really old version of Marlin FW that doesn't even support FAN AUTO OFF feature... Is there something special in REV E firmware? Nope! Just needed to change few lines of code to get it working with reverse endstop switch and different Z stepper. Works like a charm.
Please please, update Firmware on your site, I can send you my modified version if it helps
