1.) One of the "could not load world/x_y.chk" is a normal message, that's the save/loader having issues. Interesting about the weird chunk errors, I will have to figure that one out because I've not yet encountered that. I've seen visibly that chunks may glitch near (0, 0) but yeah, that's odd.
No problem, I didn't consider it demanding, I just wanted to make sure I addressed every point. I really did want to expand on the simulation, and I have a lot of ideas on how to, but as of right now it would take significant change. One idea was the "saturatedness" of a block, absorbing water from rain or water flow, and that growing crops actually requires irrigation of some sort.
For the inventory stuff, I initially wanted to do the raw count but at least it didn't look good on UI so I made it look nicer, but yeah you're right on that it needs to be more clear.