Short answers, pulled from the story.
No portrait of Shakespeare has been proven with certainty to have been painted from life. The Chandos portrait, attributed to John Taylor and dated to about 1610, was identified in a 2006 National Portrait Gallery report by Tarnya Cooper as the only painting with any real claim to have been done from life, though this remains disputed.
The two unambiguously identified representations of Shakespeare are the Droeshout engraving, which appears on the title page of the First Folio published in 1623, and the carved bust in his funerary monument at Holy Trinity Church in Stratford-upon-Avon. Both may be posthumous, as Shakespeare died in 1616.
A 2005 National Portrait Gallery investigation established the Flower portrait was a 19th-century forgery. It had been painted over an authentic 16th-century painting of a Madonna and child, and was previously believed to be the earliest surviving portrait of Shakespeare and possibly the model for the Droeshout engraving.
The Ashbourne portrait was identified as Shakespeare in 1847 and reproduced as a mezzotint, but a 1979 restoration exposed a coat of arms identifying the true sitter as Hugh Hamersley. Earlier, in 1940, X-ray and infrared analysis by Charles Wisner Barrell had suggested the sitter was Edward de Vere, 17th Earl of Oxford, but the coat of arms proved otherwise.
More than 60 portraits purporting to be of Shakespeare were offered for sale to the National Portrait Gallery within four decades of its foundation in 1856. In none of them has Shakespeare's identity been proven.
In 1964, for the 400th anniversary of Shakespeare's birth, Pablo Picasso created numerous variations on Shakespeare's face, reducing the familiar features to minimal form in a few simple lines. Louis Aragon wrote an essay to accompany the drawings.