Questions & Answers about Lei è un'amica importante?
Why is there an apostrophe in un'amica?
Would we use an apostrophe if it were a male friend (un amico)?
No, and this is a very common trap! The basic masculine word for "a" or "an" is just un. Since no letters are being dropped from un, there is no apostrophe. A male friend is simply un amico, while a female friend is un'amica.
Amica is feminine, so why does importante end in an "e" instead of an "a"?
The word order here is just "She is...". How does Italian show that this is a question?
In Italian, you don't need to flip the word order or add helper words like "is" or "does" to make a question. You just use the normal statement order (Lei è...) and raise the pitch of your voice at the end when speaking, or simply add a question mark when writing.