1) A warning from EVELYN is usually the result of a condition that is always true (or false). This can be either due to programmer error or intentional, therefor the warning.

  
  if (!GCtgOsc)
  { // reload 60Hz timer
    GCtgOsc = 10;
    GBtgLvl = !GBtgLvl;
    SB_P1_SQWOUT = GBtgLvl; // change 60Hz state P1.0  
  }
  
  if (GBtgLvl)
  {
    if  (GCtgOsc == 1)
    { // output is positive
      switch (GCmeasureState) ////// THIS IS THE ALARM LINE

I guess Evelyn is confoosing that GCtgOsc is tested false, then true WITHOUT any exit between them - is that likely?

2) I'm afraid there is no list of errors/warnings outside the source code of the compiler.
do you have a good search word?, I am sure the word 'error' appear in many other places.
I'll try a frew searches and see

Erik