OK, so spiritual and natural gifts do vary among all humans. The difference with priests and bishops is in the authority granted, not the gifts? So, a layman could actually have "better" spiritual gifts than a priest or bishop?
Holiness and knowledge are not necessarily related. You think that the holier one is, the more knowledgeable they become. On the intellectual plane, this is false.
No, I don't think that. I know people who couldn't begin to attempt to post on a thread like this whose holiness, only by my personal perception, I admire and strive to achieve. I know that difference. And I know that knowledge is not a bad thing either. I think for some people, knowledge really helps for becoming more holy because of an innate thirst that comes from God and wants to be met. Once that particular mind is fed what it needs spiritually, sanctification and holiness can proceed. I see nothing wrong with this.
For other people, they can more easily rest in truths without exhaustive examination and questioning. Good for them too. :) It all depends on how the model was built, and the beauty is that God will provide just what is needed in every case for a believer.
Certainly. Many saints of the Church were not priests. St. Francis comes to mind. Many were even, gasp, women.