Yamaha DTXpress/DTXplorer/DTXtreme

Hi all , was wondering if anyone has tried the midi connection between
the DD-50 (7 pad one piece unit) and the Dtxpress2 module? Both have a
midi in/out on it, so my question is ,  If I connected them together,
could I play the dtxpress2 sounds on the Dd-50 pads? and vice versa?
And I have a keyboard here as well with the midi in/out on it , could
this be also used?  And is there a certain setting procedure you need
to follow after hooking up the cables, internal program settings
changed or set the module to find the new instrument? please explain
:) I dont wanna sound noobish but I am not that familiar with midi
yet. Thank you in advance for any replies and help :) !