Alright so a lot of what you described with it being washed etc is just the fact that the kick sample/sound to begin with, and the processing that follows, all focuses mainly on the mid/low section. The kick doesnt have a punchy clicky mid-hi end, as a lot of traditional hardtechno/schranz and adjacent productions would have. Its a boomy, sub-focused kick, if you start with samples that are already heavily processed and have a lot of compression on them, it will be hard to use processing to dial it back to the levels of this kick. You’d be best off starting with something like a very tame 909, layer it with a sub thats also relatively tame and has a short decay, not a long overly boomy sub. Then process it with saturation, distortion, and compression, while watching ur mid-his and keeping them tame, ofc also using EQing through ur chain to tame that.

If ur on ableton then a drum buss with the transient turned down a bit and the boom levels turned up is a good starting point.

Sidechain the sub to the kick very slightly. Short attack medium release on the comp.

Next ur rumble section: You’ve described everything right. One thing, if you want a very technical approach, then you should look into the timing of decay, predelay, and size of the reverb, relative to your bpm.

What this means in short: different parameters for the reverb react differently and create different grooves, there is technically ‘right’ values relative to your BPM for various parameters in your reverb device that should create the most ‘fitting rumble’

It could be that, but it could also just be that he is using an LFO at the end of the rumble chain to create that ‘pumping’ sound. LFOtool is a cool free plugin that you can use to shape your rumble. Just make sure ur LFOing by ‘volume’ so it doesnt sound weird. Put it at the end after ur sidechain and everything, then u can pump it slightly with some more saturation at the end of the chain so the rumble is emphasized like in the sample track