1. Don't panic.
2. This is a spoiler
The yellow fruit tree, fish, and crabs are other food sources, along with mushrooms.
3. Your lovies won't starve. I had about 100 on the bush and 700 in the bin. Anything over 400 in the food bin seems safe to me, but it all depends on how large your village is.
4. Hint: Puzzles 7, 11, and 12 have to do with food for your villagers.
Don't panic, how far are you, puzzle-wise? Puzzle 7 actually requires puzzle 2, which requires some skills to achieve.