Yata

During Odium's visit on Sel there wasn't even a land based division on magic. As this features of Sel come to be caused preciselly by his murderous acts there

Probably combustion is cheaper than generate Heat with Compounding... Compounding heat is nice only for portability reasons. I doubt any industrial process will use it for actual replacement og old fashion combustion (or other source of energy)

The Shardblades happen when a Spren is so hightly tied to the physical (thanks to the bond of a certain strenght with the knight) to be able to fully manifest into the PR. Voidspren for now didn't exibited ever a bond of that intensity to allow this. Notice this is true for a true large array of Splinters not only the Rosharan one WoB as reference (little Elantris spoiler in the wob):

Like Calderis said. At the moment we know almost nothing of what happened there. Indeed it's also possible Dalinar didn't channeled Honor at all during his Realmsclap, the reaction Odium had from the scene is freaking out and yelling "WE KILLED YOU" notice the "We" that made a lot of people to think Dalinar was in some way channeling Adonalsium himself. Brandon has also always RAFOed if the "Unite them" come from Honor/SF. Also the killing a Shard by killing its/their intent/mandate/purpose/ecc... is for now completely baseless as the only instances we saw with some details didn't mention something like that at all. One is of course from Mistborn and as I don't know if the OP read it I will skip it. The other is from Odium itself fearing a surprise attack from Cultivation that could be able to murder him.... Def neither of those are about killing or interacting with the "purposes" of Shards

Maybe I am a bit late but the Shardblade VS Aluminium doubt is now solved for sure by in-book evidence. In OB a Shardblade is directly stopped by a piece of Aluminium. My own Wob someone else posted before needs probably to be updated

It's not so simple, the Dor is super compressed Investiture. It's like staying in a plasma storm (by Brandon words) so It's simply extremely dangerous to be exposed to the Dor there.

If I don't remember wrong Szeth considere Stormlight as holy and using it for illumination as a blasphemy (this from the TWotK's prologue)

I am quite sure Wax doesn't keep his Pathian earring all the time. So he didn't use both a Medallion and a Spike at the same time. But as @king of nowhere said, Telsin did that and this without any trouble or Harmony be able to control her

He stated that White sand is before quite clearly. And no I don't think there would ever be any alternative timeline in the Cosmere

I am unsure. Of what kind of discrepancies you refer to ?

Also if the protection is ancorate to a specific object instead of the space itself. I assume the object could be unbreakable but you would still suffer the pushes and be repositionable by outside forces. A last note, the statement about Aons be indipentant by their physical medium's condition is something he arose from the limited perception of Elantrians as only magic users on Sel. I assume every invested stuff would be able to disrupt the Aon if the comes in contact.

The whole issue using the "the daughter didn't inherited" as argument for the chance of a God-Queen. Is that the Daughter wasn't probably a Returned so she can't inherited the throne regardless if they would accept a queen instead of a king. Also like others already pointed. The god-kings lineage is truly too short to make any kind of extrapolation from that. There were like... 5 Godkings in the whole history and at least half of them aren't related by blood to the previous one

Vasher did nothing, the girl used magic on herself with Vasher's guidance. She used the command and her breath was involved. Vasher told her only how to do that