Yamaha DTXpress/DTXplorer/DTXtreme

OK guys....I just started tinkering with my DTXII, I wanna SAVE the 
drumkit.  I changed the voice on my snare ( to 2 layer), I wanna 
make an acoustic kit close in sound to my Pearl acoustic.  I saved 
the snare to user kit 50...I think I made a mistake...I wanna layer 
2 voices on all the pads.  Should I do ALL the pad voice changes, 
then save them?  How can I CHANGE the user kit 50 I created to 
incorporate the rest of the pads I wanna change?...Also, and here's 
a real DUMB one.  I have a prortable boombox, it's a Sony...all it 
has is an outlet for headphones...can I use this jack to plug it 
into the DTX module so I can play along with CDs?  And here's my 
third question...Would a headphone amplifier help me out?  I have 
the Yamaha RH5-ma monitor headphones.  You guys have been great in 
helping this rookie out.  Thanks again!!