Specific Fics:
a) Dean and Cas were working together in the Winchester family business of being a private investigation firm thing. Sam comes back to talk with Dean and finds out that Cas is there. Castiel was not happy about Sam leaving Dean alone. I don't remember much but Castiel and Dean were good friends and that Cas was previously employed by the another faculty before coming face-to-face with Dean due to the case where they were after the same boy before Cas decided to switch teams to work with Dean.
This one has been FOUND too!! Yay!

b) It was a curse fic. Dean and Castiel were cursed and they kept transforming every time they slept (I think) and as the curse progresses the more tired they are. They were transformed into rabbits at one point and another they had amnesia and were both in the same bed (alone in the motel room) and they may have hed sex, not sure. Sam and Gabriel save the day at the end.
IT'S BEEN FOUND!! In the comments below!

c) This one is a J2 fic. Jared is the Alpha of his pack and something happens where he is aware of Jensen from another (more brutal) pack where they had him wear a silver collar. They managed to rescue Jensen and then Jared took care of him. Jensen does not see his worth and Jared is certain that he wants Jensen as his mate and Beta. Jensen was given a job at the clinic where he took care of and/or entertained the children while waiting. Misha and Genevieve worked there too. Genevieve was working to sabotage Jensen's relationship with Jared.
FOUND! Found in the comments bellow!

General Fics:
1) Are there any fics where there are fics where Dean is a student at Hogwarts?
2) Mpreg!Dean or Jensen with graphic birth? (If there is Wincest please warn me)
3) Are there fics with Transformed!Dean that is hunted by John Winchester?
4) Fics where Dean suffers the transformation of becoming the things he hunts and dealing with it.

Gen or slash is fine, just warn me (in bold capital letters) if there's wincest. 
Destiel is preferred.
Thanks for your help!