You can add as many pictures to your collage as you like. Our users often create collages with hundreds of pictures.
Yes, you can add Pictures from Photos app.
Yes, you can export your finished collage to OS X Photos app.
You can transfer your collage to your iPhone via AirDrop and then post it to Instagram or WhatsApp from the iPhone itself.
Yes, you can create scrapbook pictures. Use the Regular Pile or Advanced Pile collage pattern to create scrapbook pictures. Learn how to use the Regular Picture Pile pattern and Advanced Pile pattern. A sample collage being designed by Advanced Pile pattern is shown below.