1. No, I didn't know that.
2. I have no objections against any of the seasons, but as I've said, that this is a totally unnessary and unrequired development for Rosie. Unlike James, Mike, Skarleoy, Rheneas & Arthur, red doesn't suit Rosie in my books, whilst her pink and grey paint does. But it's not like I'm going to merely dismiss her existence because of this.
3. I was only guessing about Season 21, so I don't know what's to happen outside of Journey Beyond Sodor - which I'm really looking forward to watch.
Neither am I going to complain about the episodes she's been in, as Rosie was another step into gender equality for railway engines, or the seasons you mentioned.
I have to admit it was nice seeing the Reverend's stories being brought back to life once again, and I wonder which books will be next. I for one, am still hoping they'll bring in the Culdee Fell Railway engines in, as I'd certainly like to hear how they'd sound (would they really have a Swiss accent like most of the Skarleoy engines have Welsh ones?)
I hope these will satisfy your mind.