Yeah, plug a floppy into the PC before you're even allowed to boot after installing a new MCA card. That was bullshit.
I remember DOS drivers being a pain. Don't remember the specifics but yeah you had to always mess with settings in config.sys when you made hardware changes. My guess is that was all the floppy did.
Nope. The floppy was there because IBM decided it was better to stick the user with the responsibility of maintaining and inserting a config floppy than to stick the makers of option cards with the bill for a config ROM. The floppy contains the information needed to perform the hardware configuration of the card. There was nothing plug-and-play about Microchannel. This permitted "automatic" configuration of cards so simple they didn't have their own CPU or even ROM, just a pile of logic on a board. EISA was the same way, except in a slot that could also accept an ISA card. The EISA contacts were deeper.
The primary thing that was shitty about the PS/2 was the value proposition. They weren't any faster than the competition (which in many case offered higher clocks) and they cost a lot more. Further, they were highly proprietary. Besides their custom and expensive and only nearly auto-configuring MCA bus, they also used ESDI HDs on a custom connector in most models. And let's not forget that the machines were well large enough to carry full-sized DIN sockets, but they chose to go to the tiny PS/2 mini-DIN instead, which offered the user nothing but additional frustration. And they went with the same connector for both keyboard and mouse, yet nobody supported freely interchanging them until Intel did it much later. (On some Intel motherboards, you can swap PS/2 KB and mouse around into the wrong sockets and they'll both still work.)
IBM realized that the market had spoken against their tactic of making Workstation-style machines with PC processors and operating systems, and created the PS/Valuepoint line, but they failed to actually meet the point at which they would have been a good value, and they failed miserably. They deserved to fail, of course. They did have some machines priced competitively with other systems, but they were the lemons of the line. Their only big hit in PCs was the Thinkpad series, which has since been sold out and ruined.
It's ironic that everything after the PC AT was some kind of failure. They even labeled their first commercial RISC processor as a PC, the PC RT. It failed in part due to branding, because it wasn't a PC. It was a workstation- or even server-class machine at the time, but it had an ISA bus.