Treamayne

Yes. Technically. Also depends on dead blades vs live blades. 
WoBs:
Hope that helps

Just like Kaladin's scar, it depends on the circumstances and the person's self-perception. WoBs:
So, for example, a Congential Disease might not be healed because it is a part of the person, but their perception would still play a part. Cancer from Lightweaving microwave radiation? If you think that is a side effect that should happen, then maybe it won't heal. Things like that. . . 

It is a Culture thing. Though we have not yet had the origin of the practice revealed yet. 
Definitely before the Ice Death (BoM Epilogue):
 
We have not yet had a Malwish viewpoint to learn more, so we only have Allik's quotes and Marasi's suppositions. BoM Ch 30:
While she may think they have a 'Political cause' the original cause may be something else, and the politics of calculated reactions may just be a cultural adaptation after-the-fact. 

I don't think that's how it works. It's more like:
Spiritual: I am a human.
Cognitive: I view myself as this kind of human.
Spiritual: I am this kind of human.
 - or - 
Spiritual: I am a human.
Cognitive: I view myself as <something other than human>.
<Inject investiture to alter spiritweb> (quantity based on type/kind/qty of change)
Spiritual: I am <something other than human>.
That's why Forgery can change some things, but cannot change other things without outside investiture (because the amount inherent to Forgery is too small for amny changes)
So, yes, there is a plausibility range to what can be affected. There are also other factors (such as Returned, being Cognitive Shadows, can more easily change some things than a normal person) - but that plausibility range is also affected by how invested the person/soul is (e. g. Yumi in Painter's body - her Spiritweb was so massively invested that it just overwrote his body while she inhabited it). 

Welcome to the Shard.
Most of Honor is still in the Spiritual Realm. When Odium pushed Devotion and Dominion into the Cognitive (resulting in the Dor) he was trying (the hard way) to prevent the Shards from gaining Sapience on their own without a Vessel. It was a huge mistake, and he learned his lesson and found a better way with Honor. 
WoBs:
Don't forget, if Honor's Investiture were not in the spiritual realm, then Dalinar's perpendicularities could not recharge spheres. . . 
Not "everything else" - Stormfather is the largest Sapiant splinter on Honor's Invesititure, not the bulk of all of Shard of Honor.

Congrats. I'm guessing iit was the AU Sixth? You're in for a treat if you ever get to read the Shadows Beneath versions (if you like that kind of thing, of course - explained at the bottom of the linked post).
I would guess there may be a fundamental realmatic similarity, but no. The Smoke coming from Amaram was due to the Unmade that he'd bonded - Yelig-Nar. The black smoke is indicative of consumed/corrupted investiture, not just Nightblood (please see below) We don't have that answer yet (please see below) We don't know how big "Hell" is, only that it is smaller than their original continent that has been abandoned to the Evil. We don't know how many species exist natively, or may be created by raising a "mainland" bird on the isles. (please see below) Patji is an Avatar of Autonomy, though it is implied that the Shardpool on Patji's island existed before Autonomy began cultivating Patji as an Avatar and may not be a Shardpool of Autonomy.(please see below) Taln was taken to Thaylen City by Amaram, since he has been hiding the Herald since the end of WoR.  WoBs and References:
Hope that helps.

The Atium Shadows (and Gold, Electrum, Malatium Shadows) aren't anything physical that depend on your eyes to "see" - the investiture is giving you information from the Spiritual Realm (where there is no time or place) and Allomancers interpret that as visual cues (but note, they do not have to "see" an Atium Shadow to react to it):
TFE Ch 14:
HoA Ch 81:
WoB:
Hope that helps

It's worth noting that even before HoA, while Keepers were generally more connected to Preservation, he already had enough of a connection to Ruin to defy orders and help topple a thousand-year empire. So, to me, his connection was there already but the events of HoA was him learning to make peace with that side of himself.
 

BLUF: AonDor needs the lines to be correct in placement; but width and other characteristics are shown to make a difference in efficacy not ability (Ch 49) and the medium doesn't matter (Ch 7).
Could you please elaborate on what version of the book you read? If not English, which translation? I ask mostly because the character you are referencing isn't named "Adonis."** That implies you may have read either a draft version or that some things might be off. Also, note that there were problems with that scene (Ch 61) originally, and it was fixed in the 10th Anniversary edition, which is now the canon version
**Note: