I think the tip to tip and greatest spread is not needed. I have never understood why they even put it on there. Maybe someone else can help with that.

As for the inside spread that is all you get credit for. If your inside spread is 17 3/8 but your longest main beam is only 16 7/8 then your credit in column 1 would only be the 16 7/8.

On an 8 point you do add the G1, G2 and G3. The "finishing off the main beam" point is part of the main beam score so that is where that point gets totalled in.

I'm not sure if that all makes sense. Hope it helps.