IIRC, villages and towns boost your trade, like mines boost your industry or farms - food output.

Printing press increased literacy in the society - especially among the merchants, which in the Middle Ages were literate. In Elizabethan London it's estimated that around 50% of the society was at least semi-literate. (Man of Rennaissance, 2007, Polish translation).

Literacy aids business transactions immensely; it allows precise record keeping (though people of Middle Ages relied on their memories and oaths), calculations (though Algebra would probably be a separate technology in the game, nevertheless Westerners started to discover Arabian mathematics and apply them). In Florence (a mercantile city) literacy rate rose from 1% in 11th century to 40% in 14th century (though it was before actual invention of printing press, nevertheless it was Italian quatrocento).

Of course, you could argue that it's a bit of putting the cart before the donkey - increased literacy created demand for more books, and printing press is not exactly necessary for merchants to draw exact ledgers. But if you assume that the in-game printing press represents also a significant literacy jump, it can be fairly realistic.