Design your bracing scheme to stiffen up the open area out in the middle expanse of panels/walls to split up box resonances/cut down on vibrations. Energy spend vibrating the box is energy not making sound.
Not so much bracing is needed in corners, like you would see in most types of construction, as the panels are already stiff there.
A good, stiff baffle is always good as that is usually the flimsiest panel, due to the speaker cutouts, etc.
Any port location is fine, just if it's on the rear, you'll want to set the speaker a few inches away from the wall instead of shoving it right up against it as is often done in cramped practice rooms, etc., so the wall doesn't "choke off" the port function, or become a part of the port, essentially making the tuning become much lower than you like.
Same goes for a side port if the cab is setup right up against another cab beside it, like the guitarists rig or something.
Ports directly behind the driver can allow some midrange off the back off the cone to "escape" to the rear, though depending in design goals, that isn't always a bad thing.
