I've been pondering a few things of late, and thought I might resurface and see what folks think of some of them.

One of those topics is inhabited wimps--specifically, how do they work? I'll try to break the question up into a few parts, so they don't all run into each other.

1. Is a wimp a living or non-living vessel? Or, does a wimp effectively become a zombie the instant that it is Inhabited, no matter what its characteristics might have been prior to Inhabitation?

2. If it is a living vessel:
A. What is the target roll to inhabit it?
B. Does it have Essence? If so, does this Essence decrease if 'ware is added? And, does it "die" (and all DNI ware become unusable by the spirit) if Essence goes negative?
C. What are the mental "base stats" of a wimp? Do they increase if the appropriate 'ware is added?
D. Does a Flesh Form also gain the DNI benefits of a Hybrid? RAW certainly (IMHO) seems to imply that this is the case, but I don't think it comes out and says it in a rules-lawyer-proof way.
E. Does an inhabiting spirit suffer any negatives (particularly, Magic decrease) from inhabiting a low-Essence living vessel, or is all pre-Inhabitation 'ware "free"?

3. If it is a non-living vessel:
A. What is the target roll (OR) to inhabit it?
B. Do its biological processes stop once disconnected from its life support? Can the spirit in any way maintain them to prevent decay or produce the illusion of life?
C. Does the spirit gain any use of 'ware, beyond purely physical (e.g., limb replacements, bone strengthening)?

Depending on the answers, inhabited wimps are either good for nothing that skillwired wageslaves can't already do, or moderately useful, or even extremely overpowered.

Now... yank the wimp's brain out, put it in a jarhead, and *then* have the spirit Inhabit the brain. Do any of these answers change? Can the spirit even "see" anything (and would fiber-optic cables tied to a retina/optic nerve "fix" the problem)?

According to Augmentation, the force-growing process used to create wimps means they never develop a functioning brain. Irreversible and total absence of brain function is the current medical standard for defining death, so a wimp should be a non-living vessel.
However, brain dead bodies can be kept "working" with a heart-lung-machine and IV nutrition; dead mothers have carried children to term. So with magic or implants the wimp should not start rotting away.

I would think though that it would be a living vessel as the organs and such from it are viable for transplanting. You can't exactly transplant a dead organ and expect it to work properly.

I guess it falls down to the divide between living and alive. It's not living per se but is alive. I would treat it as a living object for Possession or Inhabitation. Akin to a tree (used to be listed in the OR Table, not sure if it still it) and because it's force-grown, I'd bump the OR up a notch or two.

It sounds like, in either case, the spirit would not have DNI access. Is there any way to achieve that end, other than to take a sentient/sapient metahuman alive and allow/order a spirit to kill them via Inhabitation?

Which is kinda too bad, since part of what I was looking for was a way to replicate some of the nasty stuff *without* gratuitous murder (and maybe with a little customization, for those willing to pay extra for it). In short, it appears that it's terribly easy to get what you want, but only if you have no ethics; that does, unfortunately, sound about right for the setting.

Who said you have to kill them? Lotta corpses in the sixth world. In fact, I'm quite liking the idea of inhabiting a Shadowrunner who was betrayed and gunned down. You'll have their memories, might be obsessed with the idea of avenging them. His former comrades might not realise he's dead, or might resent this spirit for pretending to be him. Would there start to be a personality blurring? Where does the human stop and the spirit begin? All fun questions.

the problem here is that the jarhead is completely lacking any 'natural' senses - he's basically fed a virtual reconstruction of it's surrounding through a neural interface. Which the sprit can't use, leaving it in the equivalent of a sensory deprivation cocoon.

Well, normally the rules consider biological stuff alive (having an aura and everything), but in case of the possession rules they seem to equate "alive" and "has an Essence score".

Well, Spirit can use Astral Perception, at no penalty even. *shrug*

Not to mention the complete lack of rules regarding such an idea.

Given that a hybrid form explicitly can use DNI interfaces, I'd be very surprised if flesh forms couldn't. I'd personally be quite happy reading that into the last paragraph in the sidebar.

Not so sure there - afterall, the spriirt is possessing the brain, at most the jar around it, and not the chassis it's mounted into. Which isn't going to do good things to it's astral perception. Sort of like if you dump a possessed rat into a closed trash can. He won't be able to percept much outside.

Are you planning on using these for an actual run, or is this just a theoretical thing?

The Spirit would be possessing the Drone (or wimp) itself, possessing the brain is just stupid.