To be clear, are you using Shops or Material networks? Shops is very deprecated at this point so hopefully just typed out of habit. Regadless, this might be something better achieved through baking your curve attributes to nearest point texture on the grid similar to Entagma's example:

I don't know the answer directly, but there was a tutorial series on generating variants that sidefx posted awhile back that may be of use if you haven't already watched it - https://www.sidefx.com/tutorials/magic-market-procedural-rocks/

Sure - if you use a file cache, you can just attach a Time Shift SOP afterwards and set the frame number to whatever you want for the output (ex: go to frame 1 and then set a Time Shift SOP attached to your Vellum Sim file cache to 30 and a Time Shift SOP attached to your RBD sim's file cache to 100 and viola! you're good to go. This is generally the way to work - once you've got a sim result you like, just cache it out and work/adjust from there - no need to resimulate over and over unless you're refining your sim.

Either use a switch with $F == 100 as the true condition to wire the pieces in at that frame, or put that same expression in the Pop Source-> Birth tab's "Impulse Activation" parameter (Ideally you are caching your sim out to disk so you can shift the start of the pop sim to frame 1 and not wait 100 frames every time)

If you have a consistent identifier on the points like 'id' value or similiar that doesn't change every frame then it can be done; if not and the point count changes every frame, then not really. You can try uploading your file here, perhaps someone has a new solution to this old problem -it happens more than you'd think

I'm unable to dig into the scene but I agreed with @davpe as it seems like you pointed yourself in the right direction with your post - have you tried piping the 'flame' field into what your shader in karma is using for the 'density' field (presumably density) and adjusting from there?

You might want to try tri-planar displacement in the shader for this, should do what you're asking ex: https://www.sidefx.com/forum/topic/85715/

HDRI

Dang Olly, sorry to hear that - I hope all is well, mate!

Yes, along with a directional light for the sun, environment lights are a good choice. Clouds are dense volumes illuminated by the sun and whatever light is able to bounce off the environment surrounding them. The scattering settings on the volume shader for the clouds in particular play a large part into getting nice-looking clouds - I'm sure if you do a search you can find some SIGGRAPH papers focused on clouds or even some case studies on websites.

I'm not a redshift user, so if you're seeking RS shader advice I can't offer suggestions, but any time I've tweaked pyro volumes in post for rendering in the past it has typically been via a Volume VOP masked/driven by an attribute or volume

File -> Merge (Alt+M) will also allow you to do this

Try point order 1, 0, 2, 3 in your screencaptured addprim statement, that order appeared to work for me. My guess would be winding order of the created polygon, but again just a guess, I'm sure someone else here has the specific reason for the trouble.

It appears to be handled in the Data Bindings of the Gas Field VOP unless I'm misunderstanding it.

The explanation wasn't entirely clear to me, either - I was under the impression that Atom's suggestion was what you were after. If you're trying to remove portions of the flip mesh covering the entry break of your aquarium, extrude those shattered glass pieces out and boolean your flip mesh with them and the section of the tank you want to cut out. Basically, anywhere you want the flip mesh against the inside of your tank (or pieces of it), use that geometry to extrude out and boolean your flip mesh with, either as polygons or converted to high-res VDB and booleaned then back to polys. You tend to get help quicker if you to post at least 1 cache frame of everything zipped up with a scene for people to look at; people can often find time to open a scene up and have a quick play with solution, but not build things from scratch to post.l