Que , i get what you're trying to mean about the static. Seems like it's the clock pulses generated by the FM demodulator chip. It'll be very difficult to rectify the problem, as it'll involve filtering the output sounds with additional components to cut out pulses.
Also, when you press other buttons like Menu while listening to the radio, the extra noises you hear are because of insufficient processing power by the ATJ processor.
If you had used a computer like 7-8years ago where the fastest was only Pentium 1 - 133MHz, you'll also notice the extra noises when you play mp3s and process large data (eg transfering large files around the harddisk) at the same time. It's all due to the low capability of multitasking.
I'm not sure of the USB transfer rate, as it could be a hardware or firmware problem.
However, if you're really interested, i'll recommend USB Info at
http://www.usbinfo20.com , it's a USB diagnostic tool, and is able to benchmark real time of the USB device's speed.