What age do these visions start at? How frequent are they usually? Can one have a mystical experience without being a true mystic (e.g. nde’s, one-time encounters, etc.)?
There is no such title so far as I know so your question cannot really be answered.
Colloquially it refers to one who follows the apophatic way rather than the phatic.
There is no reason why preternatural phenomena needs to be evident.
DISCLAIMER: Catholic Answers has turned over the archive to Catholic-Questions.org and no longer owns, manages, or moderates the forums. For additional apologetics resources please visit www.catholic.com.