Inugo
For Chad I put "shikai" if you didn't notice, the bankai part was all further theory I realized after I wrote it(the word bankai).
I did notice the quotations. However, you referenced having shikai and (being able to obtain) bankai level abilities as a reason why Sado would be an Arrankar. Whether or not someone has a bankai-level attack strength isn't really evidence to suggest anything except just that--the strength of the attack.
Inugo
But in the volume where Chad is training with Renji Urahara says that his power isn't like a Shinigami or Quincy's it's that of, then he is cut off by Ichigo going Hollow in his training, or rather Ichigo's hollow face.
At most that hints that Sado is unlike a shinigami or a Quincy, which has been pretty obvious from the beginning. There is no clear indication that Urahara would have finished it with Arrankar or even Vaizard. I wont say that it doesn't lead the reader to think "Oh, maybe he was going to say Arrankar or Vaizard?" since that's what Kubo's intention probably was to do, but many a time manga-ka lead the readers astray so that the real underlying facts come out to be more surprising. (I would have never thought Isshin was a shinigami.) Not saying this is what he's done, only that is a possibility.
And for future reference, please place quotation marks around character quotes so that what you are saying will be more clearly read. I know what you said this time, but one of the next few times might be different.
Inugo
It is also stated by the Vaizard that a normal shinigami couldn't walk through the barrier so they assumed it was a Vaizard or something very much like it.
Similar would be the key word there. That doesn't necessarily make her a real Vaizard.
Though in terms of the barrier, all of Shun Shun Rikka is based upon forming shields to do different tasks. It is possible that because of this Orihime unconsciously has abilities to become immune to certain barriers.
Inugo
I also have a theory how they would have become what they did. When Orihime was saved by Ichigo in the early episodes/chapters she would have gotten her powers like they said from Ichigo meaning the shinigami traits and the hollow was there too which means Vaizard. Chad was in contact with a Hollow first and then shinigami later on, meaning he would be the opposite of Orihime which means Arrancar.
Her powers awakened due to being
around Ichigo, yes (and I'm sure being dead for an evening played a factor as well), but she did not gain shinigami-type powers from that. With both Orihime and Sado, their spiritual auras increased due to being involved so much with supernatural phenomenons in general. Their abilities are unique to themselves and as explained up to this point as not being leeched/spliced from both shinigami and Hollow.
When you mention Hollow I am unsure if you mean Acidwire (Orihime's brother), the one at the school, or if you are referring to Ichigo's Hollow side. Though in any case having a Hollow present in whatever form still makes little difference in how Orihime's abilities manifested.
How you get Vaizard that, I don't really understand. If you are referring time of contact, then by default both Orihime and Sado would be a Vaizard due to being around Ichigo and Rukia at school. Of course if Ichigo has to be in soul form in order for the shinigami side to work, then the two of them would be defaulted to Arrankar, as they were attacked first by a Hollow before Ichigo came on the scene.
Inugo
I'm not saying they had a mask to prove that but they have the traits of the Vaizard and Arrancar.
I wouldn't really call them traits more as just similarities. I cannot think of anything at current about either character that completely lines them up as an Arrankar or a Vaizard.
On a side note before this goes any further, I would like to mention that this debate is not offensive to me because we have a difference of opinions, nor am I becoming angry or even trying to entice anger. If at any time in my writing I sound as if I am angry, then that was unintentional. I do not doubt the possibility that they may have somehow become a Vaizard or an Arrankar somewhere along the way, nor that Kubo will probably spin out some crazy explanation to go along with the unveiling of such information. I'm just saying the information we have at current leads me to believe otherwise than what you theorize.
As far as I am concerned, until it is clearly explained in the manga, neither of us are truely correct or incorrect in theories that may crop up.