Hey no you can't resample while midi is playing unfortunately.. just gotta practice!
this isnt for doing 'live' btw.. just to make cool sounds to trigger later.
I kinda play live with it.. not at clubs or anything though

Still learning.
I work like this:
ESX - Single pattern
M- Base - Kick drum - Triggered by drum "1" on ESX
SP-404 - some sounds triggered by midi from esx, some pressed by hand (played by hand + hand editing delay/reverb etc effect) . ( samples like words, atmospheric like "bangggggggggg" "whoooooooosh" "clunk clunk clunk clunk cllluuuuuafnsgnklhknkkk" etc)
Then it all goes to my mixer, which has more delay + reverb on effect sends so i can add live effects to different tracks (ESX is 2 mono + 1 stereo track, SP404 1 stereo, MBase 1 mono)
So for effects I have:
404 1x multi effect
ESX 3 multi effect
Mixer 1 reverb/phaser/distortion
Delay pedal
Reverb Pedal
Flanger pedal
It's mostly about muting/unmuting parts on ESX, and altering their filter. Pressing sounds on the 404 to add extra atmosphere, and using effects to make it trippy.
As for you, I think you should make the EMX drum parts trigger the 404 single shots, plus maybe make some 'atmosphere' samples or sounds that you play by hand pressing the 404 pads when you want them to play. (and playing with 404 effect on them)
Cool to see you have a KP3 , miss mine heaps! Want another (four others actually

)
I think you should put the KP3 either after the 404 (to effect just the drum sounds) or after the master output (to effect everything)
If you put it on the master, what you can do is loop an entire song for 4 bars, then stop your emx/404, load the next song, and fade it in from the old song that is still looping on the KP4. also you can do really extreme loop/stutter/etc effects like DJ style
Samples.