I don't use the USB floppy very much (I actually borrow it from work) but haven't had any problems with it. (I mostly use USB flash drives._ It is plug and play under Windows XP and shows up as a removable drive (duh!). It is the IBM version which was in the $100 range. I have seen other ones in the $30 range, which is more reasonable. I haven't tried booting from the USB floppy but there are BIOS options that imply it can be done.
The parallel port use was all bit banging. Put out data for the LCD, pulse the E line, etc. I actually did it under Linux using a Knoppix CD (and a USB flash drive for my code) so as not to disturb the hard drive with Windows XP. I seem to remember I had to do some BIOS configuration on the parallel port so that is was where my Linux code expected to find it.
I think the USB is 1.1 - it doesn't support the 480Mb speed. It works with several different USB flash drives, my digital camera and the TI EZ430-F2013 development kit.