Re: Rin or Sakura ?
Indeed, they're base is generally the same. like Jiraiya, Naruto, Obito, Kakashi, Oro, Sasuke etc.
Sakura and her differ on personality when it comes to the aggressive factor. They do have similarities throughout the manga.
Sakura has always shown favoritism to sasuke. Rin has never shown favoritism to kakashi in the manga. However this may have to do with the fact that Obito and Kakashi had been friends for quite a while.
Sakura is pretty indifferent when it comes to Sasuke and Naruto (at least i would think so) She has given the impression to like Naruto but as the 'abusive' type you dont always share your feelings like that. Sakura is not cheerful and perceptive? I would say Sakura gets more riled up and excited than her but again personality contract.
Sakura is of course, perceptive and cheerful, how ever unlike rin she is selectively cheerful. As far as perception, Rin seems to have a much more developed and mature philosophy.
True, however Rin has showed it much more generous fashion. She made sure obito got a form even though he was someone she most likely had never met before, and was already beginning to seem like an outcast. (This is at a very young age as well). And of course, Rin's sacraficing of herself, not for kakashi, or Obito, but for the leaf village as a whole (While at the same age Sakura was willing to weigh Sasuke over the entire village).
Sakura has had to learn how other people feel before. She has done things i would consider selfless, the unconditionally kind part I can only say probably because of how she can become so worried about Naruto/Sasuke.
I am inclined to believe that she was stronger because of the higher combat statistics, as compared to the Sakura at the end of part 1. Higher speed and stamina as well and taijutsu and notably higher ninjutsu are all key in my observation. As you said her early medical prowess is impressive but her being a jinchuriki could also possibly give her an edge, though I won't assume it definitely will.
I agree though by same age comparison Rin > sakura. Just because she knew medical ninjutsu. I can't comment on her fighting Sakura as least knew a few basic jutsu plus a lil kickboxing.