Oh, first off, welcome to the new member of a large and happy cat family! Second, she looks just like my friend's cat, Blackbird (gone a long time now and I miss him as he was MY cat at a time when I lived at home with a mom very allergic to them) Birdie (as we called him) was the sweetest thing and actually came when you called. He too was an indoor/outdoor cat... but only outdoor when his meowmie or I was around to monitor him.

I have never had to deal with teaching a grown cat the litter box. Allen was young and therefore easy (but oh so finicky) and Pouncer came potty trained. Best of luck and hopefully she will follow the lead of the other cats and figure out what that funny box with smelly sand is for!