—I am prest unto it:; Ready.
—Sometimes from her eyes; In old English, sometimes is synonymous with formerly; id est, some time ago, at a certain time. It appears by the subsequent scene, that Bassanio was at Belmont with the Marquis de Montferrat, and saw Portia in her father's lifetime.
—superfluity comes sooner by white hairs,; Id est, superfluity sooner acquires white hairs—becomes old. We still say, how did he come by it—MALONE.
—the Neapolitan prince.; The Neapolitans in the time of Shakespeare were eminently skilled in all that belonged to horsemanship.