About your first question, to clarify it a bit more, you are not required to have devblog, but it is strongly encouraged to have one.
Interesting idea on how to implement the passage, and very suitable title name forerunners.
I didnt get your vision completely yet, but here are two possibilities that came to my mind when i was thinking.
Potential problem here is that if player needs to repeat same things, even if he has instructions, it is still boring doing the same thing. Therefore I can see two possible ways to fix this problem.
first one is door locked with number code. It will take some time before you can find the code for the door somewhere in the neighborhood of that door, but when you find it, you can write it right beside that door. That way one hour of play can easily squeeze into some tens of seconds of play time next time.
Another idea that came to my mind is that lets say there is some for example stone in front of some certain place. Lets say there are for example three different paths in front of that stone, and two of them have traps. Now after you figure out that road A is safe way, you can write that to the stone. Now catch in this is, that after this forerunner dies, next character comes out, but he comes many a year later to that some place, and for one reason or other, things have changed places. However, puzzles themselves havent changed, and when you in some other location than last time come to that place with that same stone, you can now read it is pathway A, and get forward instantly. So puzzles locations can change into different locations, but puzzles themselves stay the same, and this way it is more interesting to play the same place again, as all the puzzles are in new random locations each time, yet you can leave instructions for them, despite their new locations.