Hi Brewster,
I see that you have 4 drum voices and an oscillator. I guess 4 drums gives you a lot of choice but if you don't already know these modules, I would suggest you start with less. Perhaps you aren't new to modular and you know exactly what you'll get. But if you don't, it makes sense to start small and to really get to know what you have in your rack. After all, the actual modules themselves are just part of the story. It's the patching that makes everything possible. And to make the most of that patching, you need utility modules, like Jim's signature says.
I have the Rample instead of the Erica Sample Drum. If you're not planning to sample while playing, the Rample is cheaper. I haven't done an in-depth comparison, but the Erica seems to be mainly a player anyway. I really like the Rample as it gives me 4 outputs in the same 14HP as the Erica, which does 2. The default sample set is already quite extensive. Obviously, you can add your own to the SD card. The Rample also has a built-in mixer.
Are you planning to control other gear via MIDI? I saw you added the MIDI expander to Pamela. I see you also added an extra quad-VCA. That's always useful. If you look at my current rack you will see I have 4 sound sources (Rample drums, noise, bOSC analog and Plaits) but plenty of VCAs + a stereo mixer. A mixing quad-VCA like your Intellijel or my Veils works very nicely with Zadar. Zadar is also very useful with a dumb VCA like my octuple Doepfer, as you can set the max voltage in Zadar, which allows a kind of mixing anyway. I never regretted getting plenty of VCAs (I actually added the octuple Doepfer afterwards with the Doepfer decay for noise). The saying that you can never get too many VCAs is really quite true.
You asked for a flow path of modules. I tried that, indeed. My envelopes are mostly left, then the VCAs, then the sources. Finally, filter/effects are right and so is the mixer/out. But in modular, anything is possible. I have already made a patch where I VCAd a sound source with a Zadar envelope, then sent it to FX Aid, then brought its L+R outs back to Veils for yet another Zadar envelope (multi'd because I wanted the same envelope on L+R). So you can try out an order that you think will mostly work, but you'll find that there will always be exceptions.