Hello MrPete- I've got about two seconds to answer this question before the end of lunch, but i'll duck back online later this afternoon to elaborate further if necessary.
Long story short, yes- you can mount your electronic pads onto an acoustic kit- but be warned, unless you use a Yamaha acoustic rig, it can be a right pain forking out hundreds of dollars for the right hardware to do so (due to the nature of the DTX pad mounting system). I strongly suggest that you invest in some Roland PD8 pads- they are much easier (from my personal experience) to mount onto an acoustic kit. You may also have some trouble mounting your DTX drum module onto an acoustic kit- if money is no object, i suggest you pick up something like a Roland SPD-S which is much more versatile, easier to use, and easier to mount than DTX hardware.
You're right- your idea is definitely cool, and yes, you CAN play through a PA (it's AWESOME!) but it can be quite an expensive venture. You MAY also be interested in drum triggers- i'll post some more information on these later.
Good luck, catch you soon!
-KoeN
_________________
Check out some of my drumming!
http://www.youtube.com/profile?user=JoshKoen