1-1 and 1-2 are both correct, but they mean different things. The difference is in the words "fun" and "funny."
2-1, 2-2, and 2-3 are all similar. The third one is most emphatic!
3. Using "such as" is more formal than "like" (which is terribly overused and slang-y). They essentially mean the same thing, though. And you can use either "flu" or "the flu" in this particular sentence.
4 and 4-1 mean about the same thing.
5. A hospital is usually a much larger building with many departments; a clinic is usually small and closer to home. There are many more clinics than hospitals in cities and suburbs. In a hospital, you'd expect to find an emergency department, surgery department, intensive care units, recovery wards, etc., in addition to offices, reception, and gift shop. In a clinic you might find two or three rooms and far fewer employees. Here's a good answer from a wiki website: "A clinic is for short-term, non-life-threating care. A hospital is for long-term, emergency, and non-emergency care with beds."
That should be "non-life-threatening" -- to have the correct spelling!
There is a slight difference in meaning between clinic and hospital depending on where you are located. The word clinic in a medical sense can be used to mean:
a medical facility, connected with a hospital, which treats primarily outpatients. If you look at a hospital's web site these usually list the clinics:
a session of a class in medical school, in which medicine or surgery is taught by the examination and treatment of patients in the presence of the pupils.
Also, in #3, check the spelling of "spread."