If the code works...at least for now...don't mess with it. $20M p/yr is significant. Simply put, you don't know what lurks in the bowls (i.e., one refactoring could create more problems than it solves. The code can wait.
The team is another issue. That's where you need to make an immediate impact. But give them each the benefit of the doubt. Start by speaking with them individually. Then as a team. Establish a relationship(s). And then nudge by nudge make changes, changes to culture, workflow, coding standards, etc.
The team is another issue. That's where you need to make an immediate impact. But give them each the benefit of the doubt. Start by speaking with them individually. Then as a team. Establish a relationship(s). And then nudge by nudge make changes, changes to culture, workflow, coding standards, etc.