Welcome to the boards.
I love your work, and I am a huge fan of minimalistic designs. Less is more, in my opinion.
Here are some tips about cards:
The index (top left and bottom right corners) contains the value of the card (5,6,10,J,A, etc) and the suite (hearts, diamonds, spades, clubs). These are usually stacked vertically on top of one another. The reason for this is practicality and readability.
The back design is usually a two-way design, meaning you can't tell the orientation of the card no matter how you turn it. This is to allow the cards to be used in card games, and most magic tricks.
You should work with the USPCC for your deck. You have very thing borders in your design. They will whine and cry about how hard that is to do, and try to convince you not to. Ignore them and make them print with thin borders anyway.
Quality handling in a deck usually comes with the caveat that the artwork has its limits. In your case, much of the subtle light grey grid lines on the backs of the deck will not be visible on the card itself. If you want to make a purely artistic deck, USPCC is not the way to go. You may have better luck with Gemaco or Brahma (contact Don Boyer on the forums here for info about Brahma's printing).
The pip designs you made may get criticized because there has already been a deck that did them very similarly. If I were you I would ignore the criticism, since there is no patent on geometric pips, and they have been around for decades.
Keep us updated.