That old of a computer more than likely will not boot from USB. You will need to install a cd-rom to install, as far as I know. Been so long since I used 98.
1 IDE port can handle 2 ATA devices, ie;1 hdd + 1 CD-Rom or 2 hdd's. It's probably not worth messing around with, unless you can get hold of a cheap or free cd-rom.
Most new drives are DVD's which I doubt it will recognise.
I don't know... 1 IDE port and no floppy usually suggests a new computer, not an old one. Old computers always came with at least one floppy drive, but sometimes not an optical. It's really weird for a new computer to not have an optical drive though... are you sure there's no CD / DVD drive?