USB does exist in "safe" mode but your BIOS must support it. Most do not. Look for "legacy" bios options in your BIOS.
Yes, the ISA bus is being phased out. Although it's nice to have Serial/Parallel since that's all that's really needed in most cases to transfer data these interfaces are slowing our computers down. Also there are USB to Serial/Parallel interfaces now so there's really no reason to not upgrade.
The floppy connector is also useless since IIRC some BIOS's can boot from USB.
