When I had Peaches, my cockatiel, she would "hiss" more than anything else, but she never hissed at Skittles. She never reacted at all to him and I think he didn't like that cause he would attack her if she was out of her cage.
I lucked out in having her with Skittles, cause she was a "cagebody" and for whatever reason really liked being in her cage a lot. I'd take her out for a half hour or so and time and again she'd get tired of being out and go back in her cage and play with her favorite toy (which she raised hell when I took it out to clean it).lol.
As for your question about sun variations- I do know of two- there are the 'red factor' sunnies which no offense to anyone, I don't think are as pretty- they are just a real deep red. There are also the sunday conures which are a breed combo of a sun and jenday if I'm not mistaken.
But I think that just like with many other species, the colors just vary. Some have more yellow, some have more green and some have more orange. Its just how it is, I think.
