Going by the measurements, I'd say yes. HJ has bigger shoulders but smaller chest than a FJ in the same size, which means it's not meant to be worn over something thick, and the extra room in the shoulders is probably for movement.
The sleeves on the FJ can definitely be shortened. I didn't shorten mine because when I wear a jacket or a heavy knit underneath the sleeves are pulled up to the perfect length. When I'm not layering heavily then I turn back the cuffs.
I should add that my fall/winter FJ is 48S but my spring/summer one is 46S since there's no need to layer. The sleeve length on the S/S FJ is perfect for me.
Not sure. The sleeves on my 48S FJ are a bit long--longer than the sleeves on my size 48 Eidos overcoat which isn't MTO.I think the sleeves on the FJ may be a tad longer on purpose so the jacket can be worn with the cuffs turned back, which I do on occasion.
I may have had a bit of shrinkage in a couple of Inglese, but I can't remember whether they were just tighter than my other Inglese shirts (coincidentally all 38) before I washed them. They all fit a little differently from the start.