Just reporting in some more on the "wait for tool to heat up" issue.
Repetier sends this Gcode
; Activate all used extruder
M104 T0 S240
G92 E0 ; Reset extruder position
; Wait for all used extruders to reach temperature
M109 T0 S240
I see in GCodes.cpp M104 and M109 are marked as deprecated.
Since the other open source printer host software relies on Marlin standard Gcode to work according to Marlin's spec, M109 should report back T: E: W: every 1 second while heating bed and hot end.
It seems that all the firmware is sending back is "Heater 0 is on" being echoed out of "PID:

witchOn()" function in Heat.cpp