I've read that story. It was in a collection of entitled Deathbird Stories.
Or at least, the story I've read was very similar.

Have to remember though, the idea of an ice-launcher would play off a spike of ice, launched either hydrolicly or via pressurized air. Either way, funny. Now a bullet fired with an ingrained spirit with a delayed task of "destroy your vessel and remove any traces" would be interesting.

Hmm, Speed Wraith. I think anchored spells still leave signatures as normal? Plus, you can't just leave your anchoring focus lying around (or embedded in the victim). I feel like spirit powers (RAW) don't leave signatures… but they should.

She'll be smart. Right until someone shoots her in the head for being an asshole. Lived in Florida for a year and a half. Folks don't tend to take kindly to having projectiles shot at their car.

That's actually a Harlan Ellison collection and the story you're thinking about is called, "Along the Scenic Route". Very high-noon road-rage story and quite possibly something that inspired Foster to write "Why Johnny Can't Speed". I mean seriously, show me a modern sci-fi writer who wasn't inspired by Harlan Ellison or Phillip K. Dick

Yeah, but there are ways around the signature issue, and if you can figure out a way to just have the spell cast on an ordinary bullet, then masking/flexible signature/time can take care of the rest.

I would have no idea. Not that I can point to a sci-fi author that was, other than the stated assumption that they're like fish in a barrel.

Ok, what about a spirit that lays movement on an arrow? Range X Magic modifier?

Arrows fly at supersonic speed in SR anyway.

By the rules, the arrow would have the same range and damage, it would just travel faster?

First of all, the word is "Possessing", not "Inhabiting". Inhabitaion is mostly limited to insect spirits and ally spirits. Yeah, when you summon the spirit it won't know, the the rules explicitly mention that spirits know if you have a history of mistreating spirits. Mistreating a spirit now might cause other spirits to dislike you in the future.

And trust me, it sucks when your spirits don't like you. Using edge to resist summoning/binding, requiring services for every simple action, taking orders literally or bending the meaning to cause you duress. Trying to get a big mean free spirit to torch you. Spirits can be nasty.