Don't worry with the second question. I used this code and I think it works.

Code:
if (model1) 
     {pos_result = c_trace(vector(model1.x,model1.y,model1.z), vector(model1.x,model1.y-32,model1.z),USE_POLYGON);}
     if (pos_result > 0)
	   {
           //do something
           }