I think the design of the In/Expected/Actual table is the problem here. Think of each column as just an ordered list of numbers. For Addition, you just read 2 values sequentially from input and then output their sum. For example, the first 4 inputs (ABCD) are: 1, 1, 1, 2. The expected outputs are A+B (1 + 1 = 2) and C+D (1 + 2 = 3). Note that there are 2 inputs for every 1 output in that puzzle.
For the Sign Function question, try stepping through your computation while watching the "Label / Value" table on the right side. Is it possible a variable is not being erased between loops?
For Division, similar to Addition, just consider input and output as ordered lists. In the case of Division, you just need to write to @OUT twice (first the quotient, then the remainder). The instructions for each task should be explicit about the order of inputs and outputs; if they're not, let me know!