You don't need the pro version to make working drawings but it is helpful.
I used the grid on the patterns because they were shown in the plan document which is setup to proint on 11x8.5 inch paper. I left the grid on the full size patterns to use as a double check that the printer actually printed the patterns at 1:1. I could have used some other scaling tool for that, too.
No, it is unlikely that L.F. would have used a 9 foot long T-square. Instead he'd have used a 3 foot one and hooked it over the near edge of the board. Horizontals would have been struck with a triangle or by connecting marks draw in at the same distance from the paper's edge.
