Yes, I've found that it's quite difficult to get all the information across in the tutorial. Adding in some more tooltips like you mentioned might make things a bit easier for players.
With the food, you should see food spawning in every season (berries in spring, apples in summer, chestnuts in autumn, and pinecones in winter). Everything but berries requires training in the gathering skill, which is probably why nothing is being gathered in the other months. The tutorial should mention stocking up in spring if I updated it correctly, but I probably haven't made that clear enough. Also, with the fairly low rate of skill levelling limiting players to berries for a while, I might need to balance that with the availability of each food source.
Goblins not gathering stone is definitely a bug. It's probably the new equipment system messing up their pickaxe animation, similar to how the Pit's combat is experiencing issues.
Better implementation of the happiness is actually part of the next update! It ties into the social system, so that certain relationships can have perks or disadvantages like extra stamina or fights resulting in injuries. I'm still toying with a global happiness modifier for the settlement, but that won't be implemented for a while as it depends on the unimplemented decoration system.
The same goes for the effect of structure placement, which will benefit from the decoration system, advanced resource structures (like mines and farms), and also the day-night cycle I plan on implementing (where having your structures too far from one another results in time being wasted travelling).
Thank-you once again for providing feedback (it really helps me fix the problems my players encounter), and I'm glad you like my game.