well...
i dont know where you're getting this guys, but a 2x12 wont be that much louder than a single 12" .. it will move more air, so you'll percieve it as louder, but it can stay pretty damn quiet too. in fact, just as well as a 1x12 can
so if you're discouraged by a 2x12 cos you think you'll be too loud at the same settings, dont worry, you wont be at bedroom volume.
dakine, sorry, but you havent got any idea what you're talking about. the more speakers you add, the tighter the cab. if you're muddying things up, you should try EQing diferently, if that doesnt work, change the speakers. it's not "the more the muddier" if that was the case everybody'd be using a single speaker. cheap cabs tend to sound shitee though, whatever you do with it.
adding ports to it... well. yes and no. you could do it, but i dont guarantee that it will sound better. those cabs were designed with ports in mind, so they were basicaly constructed, to make them as efficient as possible