#1 With two caveats as I feel it would be relatively quite frustrating in DF where even if you try to force skilled play you'll only ever get so far, not saying it's not worth it but certain actions (like instant fail mechanics) I think will lead to more frustration then they provide actual value to the majority.. I can personally see this just creating a lot of wasted time because you're not on the job that interjects and the member who is responsible for it for whatever reason fails to do so:
1, revive will be quite close to the final boss (this is true for most content but is not always true). Consider automatically moving the revive location too, reduce the number of loading screens is always nice (black screen when you die, black screen when you get to the skip ahead point) - more like how 'most' stakes of marika are pretty much at the fog wall.
2, if a party dies a few times echo (or another buff..) applies which removes it's auto death mechanic. This could be built into the code as well so players who are doing /ooolllddd/ content unsynced would automatically gain this buff. Meaning they can't be 1 shot, as it's a bit silly to get hit for 1% your health but then get 1 shot from a 'super' move that you'd obviously survive if it wasn't for the fact it normally requires two people and was coded as an instant death mechanic- damage on these super moves could still be calculated to quite high values.. which means they'd still be scary after the party fails the instant mechanic, just not "Paladin didn't interject? Start over!".
#2 I liked the coils had a bit of a preamble before bosses. It wasn't even that long compared to something like in WoW where it was like "did you dedicate the next 2 hours? No? Get out". Even if you had to get to the locations solo first I feel it would help with content (world) building, though the short duration to reach bosses in coils was fine.