I really feel like a lot of this also could just wait till A17E is released then stable. That way all the systems are in place. Then have a basic idea of farming, but not go so in depth as nutrition. See where TFP goes with it all. Thing is, they have even said they want the game to be heavily moddable to make all kinds of play styles. When there's pretty much hundreds of play styles of this game alone, it's impossible that they will make a game where everyone is happy. There's plenty of other games where stuff is more indepth, but when I hear how much the game alone starts using so much resources, some of these indepth things would just make a lot of players frustrated since they would end up not being able to play it. There's some mods out there now, that I like the idea or have played it a little and enjoy it, I just can't play it because it really starts making things stutter (though I believe MM said they fixed that, so would help a lot). I would hate for TFP to do that to their normal game and force me to not be able to play because it just has too many resources that I can handle. So until it gets out and I can see how it runs, I'd rather it be simpler and easier on resources.
And I don't remember where I saw the post, but as for the gas and all, food brings up hunger, drinks bring up thirst, gas runs vehicles/tools. It's all one step to make something work, start adding in more steps later, get the general stuff done now. They still have a ways to go, but with the new systems in place, it shouldn't take that much longer with this great team they have.
As for working on zombies before survival, I feel like they need to. Later on, it's either zombies become zero threat because of how dumb they are currently, or if they destroy everything on a blood moon night for whatever reason (materials, boxes, chest, it all), you don't have much time to get things back up and going for such a high gamestage, so becomes a repeat death and need to start over. Once that gets balanced out, then focus on other things to start making it all tie into survival from multiple areas. As they said before, with how the system works now, you could alter the game stage based on events. So if it does get wiped out, say it drops game stage for so long so you can rebuild, or if you end up beating a blood moon night with zero damage to player, can increase more than usual.