The date of Minardil's birth appears only in The History of Middle-earth volume XII, The Peoples of Middle-earth. It cannot therefore be considered completely reliable.
2
The Elvish root min- is used for prominent objects and places, and especially towers (as for example in 'Minas Anor', the Tower of the Sun). On that basis, Minardil's name probably means 'Devoted to the Tower'. This is presumably a reference to Minas Anor, but Minardil lived at a time when the Kings still dwelt in Osgiliath during the winter, so it may potentially be a reference to the Tower of the Dome of Osgiliath.
3
The Lord of the Rings gives two contradictory accounts of the parentage of Minardil. In Appendix A, the king-lists show his father as Hyarmendacil II, but later in the same Appendix he's described as 'Minardil, son of Eldacar'. In fact, Eldacar had died 131 years before Minardil took the throne, and the text should surely read 'Minardil, great-grandson of Eldacar' (just as his assailants Angamaitë and Sangahyando were the great-grandsons of Eldacar's usurper, Castamir).