Petite Pearl questions.

What does "open trailing growth habit" refer to, or what does it signify? Is it a typical or common trait? Also I am planning on growing this cultivar on a espalier system. Am I better to prune the Petite Pearl low to the ground, and then will they grow upward into the trellis? Or am I better to grow the vine trunk to the top, and have the new growth cascade down each year?

Open trailing growth habit has two parts to it. Trailing is, well trailing meaning that the shoots droop downwards as opposed to upright growing. Open refers to the vigor of it. Open generally implies that it isn't extremely vigorous and does not produce a lot of summer laterals. So this is basically the answer to you questions on training it. Since it droops downward instead of growing upright, it does well on an upper wire training system so you are better off with your second choice. In general a lot of the hybrids are trailing whereas a lot of vinifera varieties are upright growing.

Would I want to prune similar to this foto only grow the main vine to the top of my lattice?Like if the foto was flipped upside down?

I guess that is one way of looking at it. You bring the vine to the top wire and the shoots grow either from a cane or cordon and spurs. As the shoots grow they droop down. As they get a bit of size and woodiness to them you "comb" them downwards to separate them a bit. If you look up Top Wire pruning or High Wire you can find examples. If you need help I can probably find a picture or two for you but my time is limited for such work as I am trying to finish up this years pruning season.

Thank You Grapeman for answering me. My plants come this week, and I'm in the process of building my arbor. I'll post a picture when it is built.