1. Can freeradius log accounting info in a local file, meaning not to use a sql database? If yes, how to enable that and where the log files will be (configurable?)
  You needn't use a database if you do ot want. Depend on the level of the detail you want there is the var/log/freeradius directory where you can find log files. You can find the exact directory in radiusd.conf.

2. I loaded freeradius 2.13.fc9.i386. "rpm -qa" shows that freeradius-mysql-2.1.3-1.fc9.i386 is installed. However, "which mysql: shows this command is not available. Do I need to download mysql and install it or does this version of freeradius install mysql automatically?

    You needn't. 
    In the file radiusd.conf you can see the file you need.

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Hasta las ovejas de Sietes son expertas en Windows 7. ĄConócelas!