This was a really fun challenge!
(And I'm not going to think too hard about what that says about me.)
Taxes:
I did what a few others have already described, and moved in rich Sims for their money. Judith Ward was the first, and I played most of the challenge in her house. I kept an eye out for Sims moving into expensive houses. Other highlights include Father Winter and lottery winner Bob Pancakes. (He truly was lucky - he only joined the household at the very end of the challenge, so he actually survived.) The Charm family and Vlad delivered some supernatural vibes.
Almost everyone in the household completed the money aspirations, so I got plenty of seeds for my money orchard. Here I could have done better - I didn't think to plant them until nearly the halfway point of the challenge. At the very end, I sold the house and moved to a tiny lot in Newcrest to increase the tax rate.
Death:
The house got some minor alterations: a sauna, a swimming pool, a fenced off bit of the yard. I also placed a weather machine, a robotics station and a flower arranging station. The first few days, I checked the stands in Henford-on-Bagley and the Magic Realm for death flowers and cowplant berries. For the latter, I ended up just fishing for it in Oasis Springs (thanks, recent fishing challenge!). A a death flower was found around Wednesday.
The first few days were very intense with deaths, and then it slowly petered out. Darrel Charm used his magic to start fires near Judith Ward, and to break appliances and zap Alice Spencer-Kim, who was eventually electrocuted trying to repair them (took a few days). While some Sims 'focused' on a specific death, others worked together to see who could go first. Vlad learned vampire lore to reconfigure his vampire perks, and get the 'influence emotion' one. With that, he helped with the mortification, rage and hysteria. I then had a group of mortified, and then enraged sims working the vending machines and murphy bed. Bella got crushed under a vending machine at nearly the exact moment Brant's heart exploded - it was beautiful. And after the emotional deaths were done, Vlad promptly went and killed himself (seriously, I did not even notice he was outside already).
My starter Sim, Ursula, upgraded the weather machine, and then leveled her robotics and flower arranging skills. She constructed a Servo, who did not survive for long.
For a good while, I had a couple of Sims locked in the yard in their winter clothes during a heat wave, but Eleanor ended up getting hotter inside the house near the fireplace. The same group of Sims then spent some time there during a series of thunder storms, but without any luck.
Fire: Judith Ward, fire started by Darrel
Freezing: Minerva Charm, in the swimming pool
Sauna: Mortimer Goth
Puffer fish: Eric Lewis
Murphy bed: Darrel Charm
Shame: Lily Feng
Vending machine: Bella Goth
Cardiac explosion: Brant Hecking
Electrocution: Alice Spencer-Kim
Laughter: Geoffrey Landgraab
Overexertion: Jacques Villareal
Drowning: Victor Feng
Sunlight: Vladislaus Straud
Overcharging: Emilia Ernest
Urban legend: Gemma Charm - she had been leveling her mischief ever since she moved in
Hunger: Nancy Landgraab
Overheating: Eleanor Elderberry
Stink capsule: Rohan Elderberry - the only death off lot; Thorne brought his gravestone home
Cow plant: Thorne Bailey (and later, several others)
Catastrophic meltdown: Servo Sinister - robots shouldn't go swimming
Scent of death: Jing Fen
Old age: Ekram Elderberry - right on time before the challenge ended