It is hard to tell from your picture, but if you ensure that there is nothing within about 6" of the port openings (inside and outside of the sub) and you will have no issues with air being impeded.
As far as bracing goes, if you plan on using this as a typical subwoofer, crossing over no higher than 100Hz. There will be no substantial panel resonance issues if you put another similar cross brace in above the driver and connect the two with a brace running top to bottom in the sub.
Similar to this:
Note how the bracing is on all axes XYZ, this allows for maximum efficiency.
What driver are you planning on using and what are you intended cabinet and port dimensions?
-Andrew