Scant Consolation posted:

... La Vacca ("the cow") is the name of the bell at the top of the tower of the Palazzo della Signoria, so-called because of the sound it made, not the name of the tower itself.

As for the significance of the Gonfaloniere, of the nine Priori who formed the Signoria, the Florentine government, he was the only member not representing one of the guilds (of which, as you say, the guild of the wool merchants was one of the richest and most prestigious). He was the standard bearer of the republic, and not only he but the entire Signoria would be replaced every two months, and their replacements chosen at random from a pool of eligible citizens (although as mentioned in-game, powerful citizens could manipulate that pool to favour their own supporters).