What's "rolling stone" mean?

What's the difference between "college" and "university"?

"College" and "university" are slightly different in the US. Universities usually offer degrees, such as four-year undergraduate degrees, in additional to graduate degrees like Master's degrees and PhDs. Meanwhile, colleges usually grant diplomas and offer programs less than four years in length. In general, colleges focus more on career training and the trades, whereas university programs are more centered around academic and professional training. This is changing, however, and the divide between college and university has been blurring more and more in recent years. Ex: I graduated with a college degree and now I am licensed baker. Ex: I graduated with an undergraduate degree from a university.

What's "work out" mean? Can it be used in other contexts?

"Work out" means doing physical exercises, but also means trying to come up with a solution for something or to trying and understand something better. Both are written as "work out" but the meaning of this phrasal verb will depend on the context of the sentence. Ex: John works out in the gym every day. Ex: I couldn't work out whether it was a band playing or a record.

In this case, it does not sound like an imperative sentence. But why does it start with a verb?

"I" is left out at the beginning of the sentence. The sentence should be "I think we're all set." During informal conversations, you may notice that words are left out of sentences. This is because the remainder of the sentence can stand alone and is perfectly clear without the help of other words. Words that are commonly left out are helping verbs, articles, possessives, and personal pronouns. Ex: (Do you) Know where it is? A: How's Annie? B:(She is) Not feeling well. A: How are you? B: (I am) Doing well. Ex: (Are) You ready?

What's the difference between "shore" and "coastline"?

These words are fairly similar. "Shore" and "coast" are used fairly interchangeably. They both are defined as the land that borders a large body of water. "Shores" tend to be smaller strips of land, whereas "coasts" are larger. When Americans say "West Coast," they refer to the states of Washington, Oregon, and California. Ex: We love going down to the shore during the sunset. Ex: The east coast of the United States is gorgeous. Ex: Seashells continually wash up onshore. Ex: Let's drive down the coast of California.

What does the word "instances" mean in this context? A case or a result, perhaps?

Here, "instances" means occurrences of something, an example, or, you're right, a "case." Here they're saying to indicate five examples or occurrences that are measurable. Ex: There was an instance last night where he shouted at me. Ex: There have been multiple instances of your child not handing in homework. Ex: It was an instance of good teamwork.