Radio install/removal

Hi i just bought a 94 grand prix recently and now im going to be putting my stereo system from my old car into it. First of all how do i remove the center dash piece so i can remove the old radio? Is there an ideal place that a battery cable can be run through the firewall to connect an amp?

http://www.carstereohelp.com/stereoremovalPontiacGrandPrixSt.htm

Use the antenna grommet, or run it down the frame and punch a hole where you want it to come through. Be sure to use a rubber gasket.

remove the ash tray and pull on the bottom of the center piece to unsnap it then lift up to unhook the top. the radio is held in by 3 7mm screws. How many amps do you need for the amplifier? maybe you can use the cigar lighter for power