So, yes, the original "Tray-Loader" iMac have the holes for the requisite 20 pin header on the motherboard. (I don't think the header pins are actually soldered in on any factory motherboards, or if so they're rare as hen's teeth.) Soldering in the connector allowed you to add a working floppy drive with the same capabilities as the drive in a Beige G3 as long as you were running OS 8.6 and lower, but Apple neutered the capability with OS 9. (There are conflicting reports as to whether the port was broken at the firmware level, as there's a requirement to upgrade the firmware for OS 9 on those machines, or if the driver was merely deleted from the MacOS toolbox ROM that's soft-loaded on the New World Macs. I vaguely remember seeing a thread somewhere addressing that, I don't remember the punchline.) The A and B Revs (233mhz). also have a working LocalTalk serial port, which you can access simply by unplugging the Infrared receiver. (It uses the standard DIN plug.) That was deleted on the 266/333mhz models, so if you want Appletalk on them you need to add components to the motherboard.
Technically speaking the B&W G3 uses the same Paddington I/O chip as the iMac, so if you could somehow access and free up the tied-off pins on the IC and could resurrect the drivers that once existed in the iMac firmware bundle you might be able add a "real" floppy drive to the B&W, but Don Quixote himself would probably question your sanity for taking that on.
No. Capital "N", capital "O".
The classic floppy driver software in the Mac OS toolbox ROM is called the ".Sony driver" because the developers who wrote the first version of it back in 1983 elected to name it after the source of the drives in question. (Sony invented the 3.5" format back in 1981, it didn't become a multi-vendor standard until around the time the Mac was introduced.) Most late-model floppy drives for Macs weren't manufactured by Sony, and whatever company made them had to make their drives compatible with Apple's proprietary controller, which had nothing to do with Sony. (Apple was all about proprietary floppy disk formats basically from day one; even in the cases where they bought a standard off-the-shelf mechanism, like the Shugart drives in the original Disk ][, they cooked up their own controller board instead of using a standard one. In the case of the Sony drives they bought for the Macintosh they modified the basic mechanism to behave similarly to their failed internally-designed "Twiggy" drive that had features like variable rotation speed on different tracks that normal off-the-shelf Sony microfloppy drives didn't have.)
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