You could download the manual for the 52TX, which would be quite comparable. Also, yes, the microphone should be in the package along with some form of AM antenna. However, I wouldn't worry about the useless antenna item. Focus on the warranty card, remote, etc.
If the receiver looks like it was nicely taken care of, chances are it will serve you well. However, if it looks like it has taken some forms of abuse, it might have more mileage than you contend with.