To be vivid means producing a strong or clear impression on the senses; producing distinct mental images. Essentially, she is asking if you want clearer or stronger dreams.
Hope this is helpful! I tried to describe it in the best way I could. Let me know if you have any questions.
A sentence fragment is a incomplete sentence like, one that doesn't fully explain its self. fragment = came to the house, complete = Lilly came to the house to visit.
