Stocks are set to exit October with a tailwind but will immediately face a Federal Reserve meeting in the first days of November that could help decide the course of trading for the rest of the year. The Fed is widely expected to raise its target fed funds rate by three-quarters of a point Wednesday, but it's what central bankers signal about December and later that will matter most. Some economists expect that by the mid-December meeting, the Fed will be ready to scale back the size of its rate hiking to a half percentage point, or 50 basis points….