The dev included some hints (in text files) with the game. They answer some of the questions being asked here.
Other than that, here are a few things from memory (played the original right when it came out):
To unlock pregnancy, you basically need to do everything you can, see every scene available other than the endings. There is a counter that needs to get to 28, and it's incremented when you finish a main villager's series of scenes, and when you see the various mini events. Basically you have to fill out the recall room other than the endings. Then you can open the chest in the recall room which gives you a key to the bureau in her room, which will unlock pregnancy when you interact with it. You can interact with it again to set the pregnancy chance to 0%, 50%, or 100%. (It's set to 50% by default)
Cicadas/small bug: The small/tiny bug can be gotten multiple times, it is needed for two quests (ghost guy and bug collector guy after you do his 6 cicadas quest). It is also NOT one of the 6 cicadas needed for the 6 cicadas quest. One of the cicadas for the 6 cicadas quest can only be found at night. Their locations are in the help files the dev included with the game.