No evidence, its just what I've noticed with my team and other teams I have had a look at. So it could be wrong, but I just wrote what I thought :)
For the first question, I believe that the further away you are from the basket, the more important Jump Range becomes, if you are at the free throw line, which is around 15 feet, then you are not very far from the basket and I believe that an 8 JR is sufficient at this point and the 15 JS will significantly increase your chance of making the shot. On the contrary, the 13 JS would still be a good chance to make the shot, however I think that the 10 JR doesn't increase your chance of making the shot over an 8 JR (or at least not enough to make a noticeable difference).
My understanding of JR is that it doesn't add to your ability to make a shot, but it just means that as you get further away from the basket your ability to make the shot isn't hampered by as much. So at the free throw line having 8 JR is no different to having 20 JS as at this distance the shot isn't hampered by much. However, the 2 extra pops on JS will mean that his shooting skill is higher from close distances.
Not sure if I explained what I meant well....let me know if you don't understand.
As for the second question, I think that at the free throw line, outside defence is still used more prominently in calculating defence than inside defence. I consider inside defence to be used more prominently in the 10 feet or closer area to the basket. This is where inside shots, layups etc are made from so inside defence matters more. However at the free throw line, outside defence is still favoured and so naturally the player with more outside defence is going to defend better.
Do you disagree?