Taking the raod less travelled...I can definitely respect that.
In my experiments with flours with varying amounts of protein, you'll definitely get a more tender crumb with a lower protein flour, but you will also typically get a denser and less airy crumb. If all things being equal, you get a softer texture but the crumb matrix tends to be tighter and the overall crumb less airy.
You (theorectically) should be able to make a tender crumb using almost any flour or blend of flours if you build the gluten properly. But that is much easier said than done for sure. How are you mixing your dough? By hand or mixer?
As far as adding in melted shortening, I think most bakers add oil and fats towards the end of the mixing protocol. For my specific methods which entails using a moderate amount of mixing with a mixer initially and finishing the dough with hand folds separated by intermittent rest periods, I have found that it makes very little difference if any when shortening is added upfront or towards the end while the dough is in the mixer.
As far as oil vs shortening. I did about 4 seperate side by side comparisons between the 2 and the shortening dough always produce a noticeably superior crust and crumb. For my taste, the shortening in small amounts 2-3%, produces a slightly drier crust than oil. It's just as tender, but you wouldn't even notice it's there unless I told you.
It took me several years of endless experiments (3-4/wk every week) to learn how to make a tender crust and crumb without use of oil or shortening. It was a huge challenge for me at the time and I bought into the purist mentality of only flour, water, salt, and yeast for dough. These days, I find that a bit silly. For me, adding a small amount of shortening is like using the simple button. It just makes life easier.