Yamaha DTXpress/DTXplorer/DTXtreme

Can anyone give me advice on a couple of things.  I have a dtxpress 
II and I've added another module, (a used Alesis D4) and a few extra 
pads.  I really don't know how to use the Alesis D4.  I didn't get a 
manual but I downloaded one from the internet and there seems to be 
some info missing.  I can't figure out how to assign a pad the voice 
I want.  I tried doing it the way the dtxpress module works, but 
obviously the D4 uses some other method.  Can anyone tell me what it 
is?

Also, I'm getting cross talk between the modules.  I hit a pad 
connected to the dtxpress, and and Alesis pad sounds as well, & vice 
versa.  What's the best way to control that?

Last question: At church, I play an older dtxpress.  We've ordred a 
couple of extra pads and another used dtxpress module in order to 
have a few more drum voices availble.  I'm going to have to mount the 
new pads on the same arm(s) as the existing pads from the existing 
module.  I expect I'm going to have some crosstalk issues there too.  
Any advice to head off that problem?