As far as I know, MIDI uses 3 pins ONLY of the 5 pin 180 degree DIN plug, the other two pins (#4 and #5) are not used. The wire connector colours are not relevant in any way, so could be anything. Pin 1 at one end is connected to pin one at the other, 2 to 2 and 3 to 3. A MIDI cable can be connected either way around, there should be no difference. A cable using pin 5 as you describe might relate to some special purpose, but would be somewhat hit-and-miss for normal midi use, i.e. it might work for some things but not for others.
MIDI is RS232, but the Baud Rate is different to those used for normal serial comms work. Most normal comms equipment does not support the MIDI rate.
Never heard of anything checking the TTL value, I believe that MIDI will still work normally over a wide range of signal strengths.