• how does the user change the classical model of typography?

The classical model of typographer is what famously described as the "crystal goblet" by Beatrice Warde where the designer dominates the control of the text while trying to make themselves invisible. Nowadays, however, the users actively engage in making meanings, and typography "becomes a mode of interpretation". The designer and readers compete for the role of the author, making the authorship conspicuous instead of invisible.

• what is meant by “we may play the text, but it is also playing us”?

The content we put out (we play the text) alters our ways of seeing and our habits of thinking (it is also playing us). Lupton thinks that how texts are used becomes more important than what they mean; it's echoing the message by Marshall McLuhan that says medium is the message. The environment nowadays is becoming more interactive which provides the users a degree of control. As they respond and react to the signals of the system, the text is added other layers and layers of meaning and interpretation.

• compare the reader/user of digital vs print, list two myths/assumptions

Screen readers are more impatient than print readers, because it is assumed that people need to feel more productive on screen rather than contemplative, and the text on screen is inherently more difficult to read. However, HCI studies in 1980 have shown that the efficiency of reading black text on white is just the same for the screen and the print. 
Icons are a more universal mode of communication than text. However, text can actually often provide a more specific and understandable cue than a picture. Especially in the age of coding, text has become a more powerful tool than image as it's searchable, translatable, and capable of being reformatted.