Iris: I will try to answer your question about “small” and “little” here, where there is more room to write.
When referring to physical size, both “small” and “little” mean the same thing: “My car is too small/little to comfortably seat six people.”
However, sometimes the word “little” is used, because “little” is better to express emotion in a particular context. (1) “Look at the small dog. He looks hungry.” The first sentence simply tells us that the dog is physically small. (2) "Look at the little dog. He looks hungry.” By using “little” in the first sentence, we have expressed a bit of sympathy and tenderness towards the hungry dog.
“Little” can also be used to express other emotions, such as scorn. Imagine a man who is two meters tall, and who weighs 100 kilos. He is obviously a physically big man. Now imagine he is a mean bully, who treats everyone else badly. You can say, “He’s such a little man.” Here, “little” doesn’t mean small in physical size. Rather, it means narrow-minded, petty, mean, etc.
“Little” can also mean limited in duration. “I have to leave soon. Not because I want to. But because I have limited time.” You could not say, “I have small time.”
The differences between "small" and "little" are much more numerous and sometimes more subtle than I can explain. If you google “small” vs. “little”, you will find numerous discussions of this issue. I hope you will find more help there.