Hearthpwn

It's definitely not essential. A very similar card may be Cabal Courier, but you can replace it with any card you feel is a good fit for the deck.

They are both there to finish out games and heal quickly. Jaraxxus is also there to be another demon. Jaraxxus isn't really supposed to be the decks main win condition so I wouldn't worry about him too much. Just keep in kind that against decks with lots of burst I never play Jaraxxus and pull it off of Krul. I also only really play Jaraxxus on an empty board. 

Battletag: Shadyape #11963
Region: NA
Trade Only?: Yes, you go first.

Done

1. In this list in perticular, Barnes has won me so many games due to the high chance of pulling something good, or pulling something big and using ancestral spirit on it. I've tried cutting it but the deck is just better. Maybe if you ran stonehill defenders it would get a little worse.

2. Before this version, I was running a more midrangey version of the deck and volcano absolutely clogged my hand. With this version it isn't as much of an issue, but it still can be probalematic. On the other hand, if you don't have a clear on queue you lose. Maybe a solution would be to cut some of the other situational cards you mentioned for more card draw which this deck definitely could use more of.

3. I had stonehill defenders in the deck and initially liked them, but after cutting them in this list for loothoarders and adding some more late game with The Lich King I just began doing better.

Overall, I feel as if the deck would be viable if it had a little more healing to stabilize and it had more card draw.

Edit: I added 2x Acolyte and took out ancestral spirit. I'm also trying Hallazeal over the Lich King but I'm not sure about that yet. The added card draw definitely makes the deck better. Also, Acolyte combos well with volcano.

1. You can go 0-3 with any deck, especially the first time you play it since there's a high chance one won't play the deck optimally if they haven't had experience with it. Also, with such a low sample size you can easily queue into the worst matchups everygame if you're unlucky.

2. More importantly, it's a theorycraft. The only way people figure out meta decks is by experimenting. If you like to win go play tokem Shaman. For many people, experimenting and playing off meta decks is more fun.

The matchup against highlander priest is dependent on how well the priest draws. If they draw Raza and Anduin on 5 and 8 respectively, you probably lose. Otherwise, the matchup isnt bad. Hunter and Mage are both good matchups. If you find that you are struggling somewhat against those two, all you have to do is tech in more healing. 

Why did you end up going with one Sprint and one Gadget? Did you try both and it just seemed to work better this way? I feel like if would hurt consistency having a lot of one-ofs, but then again, I haven't played the deck and there's a ton of card draw so I wouldn't really know.

Spirit Echo is a very good card, but I'm not sure how well it would do in this deck. The card is kinda slow and this deck already has good win conditions. Also, I would rather have card draw than Spirit Echo to gain card advantage since there are many important cards you need to draw.

N'Zoth clearly becomes a little worse without Cairne, but any strong midrange card will probably work. I would recommend something like Hallazeal, Elise, or Skulking Geist since there arent really any other big deathrattles worth running in standard. Stonehill defender is also a very good card in this deck so you could give those a try.

Shallow Gravedigger seems like an auto include in quest priest. Also, you're never gonna finish the quest against pirate warrior and sometimes burn mage so priest of the feast or greater healing potion seems essential. Finally, running one shadow visions is just handicapping yourself since its such a good card.

Innervate is fine the way that it is. Every class has some overpowered cards that define it's identity. Now if druid also had good removal then maybe a change to innervate would be necessary.

Unfortunately, no. If you've already played five minions with five or more attack, you've probably won or at the very least don't need the quest reward. Also, it makes your matchup against aggro worse since you have a lower chance to draw ramp/removal in the mulligan.

In my opinion, mire keeper is a great card. The only reason no one plays them in any popular druid decks is because it is not good in aggro, and jade druid doesn't want to play it when they have jade blossom. I would highly recommend keeping them in the deck, or at least replacing them with some early game minion and not lunar visions. Tyrantus is cool though. I personally don't own him so I haven't tried it out. 

I would say that the draw option has been the more common choice for me since card advantage is very important in this deck. The 2 mana crystals can be game winning against aggro however. It all has to do with the minions in your hand and the amount of total cards in your hand. No matter what option you choose, you have to make sure that you have a strong play next turn.

I can always answer more questions about the play style in the comments.