How can I pass multiple variables to a function?
You may create a struct with "x" elements, one for each LED:

struct ArrayOfBooleans {
   bool array[4];
};

ArrayOfBooleans myOutputArray;
myOutputArray.array[0] = true;
myOutputArray.array[1] = true;
myOutputArray.array[2] = false;
myOutputArray.array[3] = true;

lightEmUp(myOutputArray);

void lightEmUp(ArrayOfBooleans myOutputArray) {
   bool isFirstLightOn = myOutputArray.array[0];
   // etc
}


NoTE: If you run into Exception 9 issues (using this logic on another board), please check this answer to another post