If I was restricted to one rod for bass, it would have to be a 7ft. medium-heavy fast action. I'm 6'5", so I can even fish topwater with a 7ft. rod. If you were a shorter guy, you would probably want a 6 or 6.5ft. rod. More important than the length is the action. Light baits work best with a medium power, big baits with a heavy power, but you can cast anything from a 1/4oz. minnowbait to a 1oz. topwater with a medium-heavy power rod. The fast action might be a bit much for some guys when it comes to spinnerbaits and cranks, but is a real necessity for soft plastics. I have a rod like this...it is a Fenwick HMX Crankbait/fast tip. There's a Pflueger President 6.4to1 hangin' on it....this is the most versatile bass combo I've ever fished. If you were looking for one outfit to cover it all, look no further!
As far as tackle, I'd start with an assortment of spinnerbaits, crankbaits, and soft plastics. That should keep you busy...well...until you see some bass bustin' baifish on top! Then you're into the world of topwater...no turning back now!
I would recommend keeping it simple for the line choice. Choose a specialty line to enhance one technique, and you're gonna hurt three others. Your best bet here is go with plain old MONO
and save the headaches. I like good ol' Trilene, but there are many other good lines also. I think 12 or 15lb. test would be a good all around choice.