Flubaroo will not do what you want as far as skipping questions that are blank. Are you saying the total of possible points should be based on the number of questions answered?
You could add an answer of Skip but then all the students will answer that if they realize that it will be graded as correct.
I don't know if you can trick Flubaroo into treating a Blank or Null as correct by using the %or operator. I would try putting the Blank inside of single or double quotes to see if that works. Answer row. Cat %or ' '. I don't have time to test right now.
Another option is to grade your own quiz and report the data using Autocrat or FormMule. You can make any rules you can put into a formula. See
Comparison. There are examples at the bottom.
Good Luck! Let us know what you did.