Yupgp, I hope that you can make it on your next submission.  What could help you, if you don't mind some straight answers, is the SS critique forum.  People are there to normally help and support each other.  It will also give you the sense of what is expected to submit.  Since you already are registered up there, you can get some feedback on your own pictures from your first batch.  Don't forget to have at least part of it as a crop at 100%.

The SS standard has become harder with time, so I'm quite sure that most of the first 10 pictures I submitted wouldn't be approved now.  I had to adjust and improve my skills to fit in the more demanding stock expectations, and it's still a work in progress for me at this point.

All the best to you, I'll be glad to see you around.

A lot, in fact most, of my pictures have shallow DOF and they were accepted with no problems at Shutterstock.  Obviously an extremely shallow DOF, to the point that not much is in focus but a solitary point, is going too far... but you don't have to have your entire picture in focus by any means.  In fact, a lot of times a shallow DOF actually works better.... depending on the use of the pic.

Work on the noise issue as that will result in rejections pretty quick.