Правильно ли написаны вопросы? 1)What does the term “сollege” mean? 2)What is a liberal art institutions? 3)what is community

1) What does the term “сollege” mean? - correct;

2) What are liberal art institutions? - without "a", as the Noun is in plural ("institutions");

3) What is a community college? - with "a", as the Noun is in singular ("college");

4) What is the academic calendar for a university in the US? - with "a", as the Noun is in singular ("university") and has the meaning "any";

5) Why is it not so easy to stay in university? - introductory "it is" in the converted form (as it's a question) is omitted.