The Morphagene should 'play nice' with the Eloquencer's CV outputs as well as the gating. As to exactly how to do it, that's best answered by yourself once the modules are in hand, as your best method might not be the same as mine. So...what I would suggest is to add a trigger sequencer, potentially clocked by Pamela's, to deal with dedicated drum triggers as well as triggering any envelopes, etc. The Pamela's should probably be locked to an incoming MIDI clock via that interface, which you can either pass from the Pamela's to the Eloquencer, or you can mult the MIDI interface's master clock to both. Eloquencer is also excellent for the Noise Eng. module.
As for which drums...hmm...that's more a matter of what sort of music you're trying to do. I'd suggest spending a good bit of time researching the drum modules on here, particularly if the listings have links to video/audio material where you can get a good idea of what sounds you're going to get. Also, you'll want a few more submix channels as the amount of drum modules grows; I'm also not sure that the Mixup is the right device for the job here, as something with actual pan controls would make more sense for your final stereo mixer.