2 cabinets sound better and louder than one, in a normal configuration. The rule is less than one half wave length apart, which is why vertical stacking is better for multiple cabs. Greater distance and you lose the volume benefit of multiple cabinets. Also, floor coupling gives smoother bass with less frequency peaks, like the old Acoustic Research cabinets. Place one cabinet on a brace or stand facing the floor, or build a cabinet like the one Sundogue built. Porting will give you greater sound volume, because you get the advantage of the response from the rear of the speaker. A sealed cab gives great sound (tone), but is inefficient and actually uses the air pressure building up in the cab to dampen the speaker cone, making it less efficient, therefore requiring a bigger box to minimize the dampening effect. Port placement is voluntary...makes no difference where the port is. It will still do its job. Brace your cabinet well to eliminate resonance, and you can essentially get away with building a cubic box with good material that will perform well. Dampen with batting or fiberglass insulation. The highest frequency that most basses reproduce is under 700 Hz, so a low crossover setting should be adequate, if you use one, but not necessary. A high quality speaker such as Bag End, EV, JBL,Eminence (be careful, because Eminence also builds low end stuff), or if you can get iit, Meyer (check ebay for used), should be used. The Chinese stuff is iffy. Keep studying and learn the difference between bass reflex, horn, transmission line, bandpass, and quarterwave cabinets. There are cabinet builders on this site who have their own prejudices and ideas, and there are afficionados of those guys. They probably make good stuff, but I have found their responses to be minimally helpful and guarded, and have spent quite a bit of time perusing speaker company websites, designers, talked to speaker manufacturers including EV, Eminence, Bag End, Thunderfunk (recently building cabinets now), Meyer (not very helpful, but great speakers) and several others, including some of the guys here, to get the information that I am passing on to you. Good luck, have fun, and hope your project works out well.