| Quote #4
I pray you, sir, let him go while the humour lasts.
When Grumio notes that Katherine doesn't have a chance against Petruchio, he lets on that perhaps Petruchio's (future) transformation from an average guy to a domineering bully, who is more of a "shrew" than Kate, is more common than Petruchio lets on. It seems that P has played this game before.
| Quote #5
I'll tell you what sir, an she
When Grumio assures Hortensio that Petruchio will beat Kate in a verbal battle of wits, he suggests that Petruchio's words, his "figures" of speech, have the power to physically alter Kate's appearance. (Like acid might burn and transform a person's face.) This anticipates Kate's transformation from railing shrew to an obedient wife. And though Petruchio never lays a hand on Kate, his taming tactics – starvation, forced sleep deprivation, etc. – do cause Kate to physically suffer, just as acid would.
| Quote #6
Young budding virgin, fair and fresh and sweet,
It's no surprise that the moment of Kate's so-called "transformation" (the moment Petruchio breaks her will and tames her) occurs when she and Petruchio transform an old man into a "budding virgin." Part of what makes Kate a new kind of person is her ability to pretend, just like an actor.