Can't save all photos to iPad air from photostream It might sound strange but trying to save the photo portfolios to my iPad using photostream to transfer from iMac, noticed that in one of the folders not all the photos were saved.

Repeated several times, the weird thing is that is always the same number of photos missing from photo stream to the destination folder. I really don't know how to address this problem.
I don't understand your question completely, but I'm pretty sure:

You have reached the sharing limit on Photo Stream or iCloud. Apparently you can only transfer so many photos per hour, or per day. (Read more in the Apple support article.)

It might also be that there is a limit on your iPad for memory space. Is your iPad memory full?