So apparently you don't even need that my_files_only code since Access has a setting for that. I tested it and I only see the images that user uploaded... so one thing down, two to go...
Now I still don't know how to limit the number of images per field. The code I had to limit was this below, but since the change of being able to add multiple images at once, the code does not work.
1) Use WordPress built-in media manager to upload/crop the images as I mentioned above: With WordPress built-in media manager user can click link "Edit Image", and crop the image manually, see screenshot: crop.JPG
I don't see an option to edit the photo, look at the screenshot. I have set properly in Access to allow Authors to edit their images. Look at the screenshot.
Yes, you are right, there isn't such kind of built-in feature within Toolset Forms plugin, it needs custom codes.
You can try these:
1) Change the CSS class name to field slug "fotos-para-anuncio", for example: