If your having trouble moving from standard to heavy like I was when I started, picka fast song (175 BPMS and up) and beat it on light 3 times, standard 3 times, then try over an dover till you beat it on heavy. The more heavy song you play, you'll notice the slower ones are the harder ones... I have the X-box version of the game, so I don't know if it has the same songs, but My first song I passed on Heavy was "Candy." Also, on the ps2 version, do you have to unlock certain songs like MAX 300, and Paranoia Rebirth (I know you have Paranoia Eternal... it's on every DDR game I've seen *fun song*)
And on getting triple A's i can only do that on light, double A on standard, and single A on heavy... I've been talking so much now I have do go play it! LOL