Yo Dvsbruschko- You are way confused. Cardioid is a polar pattern, which is to say what directions the microphone picks up in. Cardioid means heart shaped, so the mic picks up what's in front of it more, and sensitivity drops off to the side and rear. Hypercardioid is the same deal, but narrower, with minimum off axis response, as close to a laser beam as a mic can get. Supercardioid or wide cardioid picks up more to the sides, but is still directional. Omnidirectional is basically a 360 degree sphere, as even as possible in all directions. Figure of 8 (figure 8) picks up evenly to the front and rear, but much less to the sides.
Dynamic microphones have a different electrical operating principle than a condenser mic. Their generally lower output and sensitivity has made them an industry standard for mic'ing guitar cabs for many years. Before I can tell you what the AKG is good for, you'll have to tell me the model #, AKG makes a lot of mics. That SM58, though- First, unscrew the little ball off the top and set it aside. Then place it tight up to one of the speakers of that half stack. Put the mic right up to the grill, without touching, pointed just a little off center. Then, wearing headphones, have someone play while you move the mic closer to the center and away from it, changing the angle of the mic to the speaker cone, and listen to the sound change, which it will. If the sound of the amp is good, there will be a "sweet spot" where you pick up just the sound you're looking for. All you have to do is find it. For the record, the SM58 is a *cardioid* *dynamic* microphone, and it is a very good mic for recording electric guitars.-Richie