The difference is that precedent can guide a judge's decision, it doesn't force it.
Likewise in civil law the judge isn't simply a referee, they're meant to actively investigate. While in common law lawyers get to do a big show by asking various questions, in civil law the questions are asked by the judge and the lawyers only exist to make an argument.
No, the judges rule with what they have, based on the case’s specifics and the "legislator’s intent" underpinning existing law.
Although it does not become law, their ruling can be used as precedent in later similar cases, until the legislator catches up.