That's awesome! Hope it was a good deal for both you and the seller.
The deal with the center channel is the port can be removed for aesthetics. There isn't a benefit when doing so, in fact, there's a slight penalty. But only slight. The spectral match is still very good from 200Hz up, and below that you're in the modal range anyway. So it's not bad, and it looks better if the left and right speakers are made in mirror images - each with the tweeter towards the outside. The center speaker can have the tweeter centered when the port is removed.
Best to have the mains 12" to 15" up off the floor, with flanking subs placed slightly behind and beside the mains, sitting on the floor so slightly below the mains too. Left main has a left flanking sub and right has a right sub. Each is passed a (100Hz second-order) low-passed copy of the signal sent to the main it is flanking. This approach mitigates SBIR and higher-frequency room modes and also compensates for baffle step while providing increased bass extension.