'Slow down, you move too fast...you got to make the morning last just...'
(famous line from an old 60s song - but very appropriate here)
Let's take your questions one at a time (anything in blue is a link);
a. There are many programs out there for the 300. Most people start off with the Uniden Advanced System director (or UASD), which is available from the Uniden website (which as I understand it, has been up and down the last couple of days..). However there are also the freeware FreeScan and BCTool. No doubt that ARC330 (available from Scanner Master) is the champ, and there are others too...All of these are popular, and some keep more than 1 package on their machines for different purposes. You can get a list of links in the software section of:
http://wiki.radioreference.com/index.php/BR330T
b. Since the 330 has been discontinued, I kinda doubt that there are any new Firmware releases; however, if you register your radio at the Uniden website, you can find this out for yourself. If a firmware update is needed we'll answer that later...
c. The biggest hangups with USB cables is not matching speed, but making sure you assign an open COM port. Check with Device Manager to insure that when you load the USB software, you are assigning to a port that is not being used by something else. There are different flavors of Windows, so where device manager is may vary; under XP, click on Control Panel, double click System, then Hardware.
73 Mike