So for now (and things will change in the long run ^^) I´d look at your setup this way:
Without computer PNW is a good choice, although I don´t have one. My concept is around a drum machine on steroids which integrates into a bigger setup, so external clock and computer. I also decided to eliminate hp as a limiting factor, which led to different choices. Maybe others can chime in on function per hp efficiency.
That said, for sequencing with variations: Metron has probability, so a certain amount of randomness is already in. It´s probably too much of an hp hog in 84, but I predict your system may grow bigger over time :D. Take a look at Euclidian Circles (vpme), Knight´s Gallop (shakmat) and Numeric or Zularic Repetitor (noise engineering). Reserve one or two tracks/sequencers for accents so you can treat them as split from the gate patterns if you want to. Like: standard 16th HH, then add a 7 step accent pattern or whatnot.
No sampling, but loops :) does not compute ^^.
As for mixing and effects, it depends on your workflow. For me, Kick is essential and this also comes with a rumble chain. I played around in Ableton to find out what I need and then built that with modules. That alone could eat 84hp ^^. A quick and very reliable way for kick is the jomox modbase, but there are many other good choices as well. It´s a deep module though, check whether it fits your case. I like my mutant drum modules as well, less experimental than, say, wmd, but spot on if your sounds are "around x0x". Effects depend. You may want to get some shared options like delay and reverb, but also have dedicated fx for "that clap every 4 bars". Also think about whether you really want to mix IN the case. The biggest reason would be mix automation/modulation. If you don´t really do that, an external mixer is way cheaper and offers more function wise (like 3-4 band eq, a number if aux channels etc). For Euro, I can recommend wmd performance mixer (no eq though) and befaco hexmix).
I don´t necessarily think a compressor needs to be slapped on everything, but found that it can help shaping the transients beyond what is normally given in any sound source. My advice is to build things in virtual, see what works, what you like and then build that in hardware. For example, I use a dedicated compressor (Lollipop) on Kick and Clap mainly to shape transient and texture. MSCL on the other hand is sitting on the drum+bass submix for saturation and pump.
Percussions: You will get most out of modules that offer a high level of modulation control. Plonk comes to mind. I´m sure there is tons of other options, I just found the name of the module is reason enough :D.
Oh and the most general advice: For every hp of sound plan 2-4hp of helper modules to really get to the fun stuff. For example: I 1:7 mult the modbase output to 3 elements of rumble chain, so I can play with those 4 elements. Adding some CV to the various components to introduce changes over 2, 4 or 8 bars is fun. Also multing the kick trigger signal to activate envelopes+VCAs, poor man´s compressor. Likewise, using metrons gates, triggers and CVs to rhythmically modulate sound changes... you get the idea. While a compressor would pump based on the actual audio signal, ENV+VCA could either follow a trigger pattern of a sound or could do something slightly - or completely - different. Put that on a pad sound for example... etc.
In my book using MSCL to just avoid clipping is an abuse :D. Just use an attenuator/vca/mixer and proper gainstaging if you run into level issues (although those can be nice in the sense of saturation).