The absolute latest firmware version is 1.07. I'd suggest that you run 1.06 or later.
For programming software, I use and recommend WIN97 (www.starrsoft.com). You will also need a USB cable to do either. You can get one from RadioShack (20-047), GRE or other online sources. Note that all serial cables are not the same and you need one specifically for the PSR-300/PSR-400/PRO-164/PRO-197. The old COM version cable which worked on earlier scanners like the PRO-97 does not work on the PSR-300/400. The cable at RS is ~$35.