I believe that I cured the problem.
Working in a test copy of the course, I set all the weights to 0 in the Grader Report/Gradebook set up. All categories and the course total are now 0. When I export to Excel, they are 0 and now my calculation will work without all the hassle of removing columns or unchecking options just before I export to Excel.
To answer your first question: I dropped the K-12 Weighted Grading system for something that is much more real world qualifying. I give points as grades. Depending on the number of graded activities I give, students can earn around 4000 points for their work. One assignment can have a value of 37 maximum points for a job well done while part of the term project can earn 739 points. One could call it weighting, but it is not based on that archaic 100% idea.
I was always amused that the value that is used in the calculation of the category total is not based on the value you select in a scale. It is based on the number of entries in the scale. For example, if I have a scale of even numbers {0,2,4,6,8,10,12,14} Moodle sees 7 for the calculations because the are 8 (compensating for 0" entries in the scale.
I red a thread here, or somewhere else, about this and it set me to thinking.
Anyway, the Category and Course total issue has been solved.....