Unfortunately, it depends on the game.
As clok mentioned, several games - especially earlier Amiga games - simply assumed that most users had a A500 Amiga with just the inbuilt drive, as it was unusual to have more than 1 floppy drive.
However, a lot of games will take advantage of additional drives. There are very, very few games that won't "work" with 2 or more floppy drives, so don't worry about that.
You could be confused with "diskswapper" and Floppy drives:
WinUae supports 1-4 emulated floppy drives attached to the emulated Amiga. It has 2 attached by default. You can insert 1-4 floppy images either in each set of saved settings, or on the fly by pressing F12 (This is not very useful for cabs though).
The 'diskswapper' is simply a WinUae feature that lets you have up to 20 disk images ready to swap in which can be called instantly by Hotkeys on the fly during emulation. Its simply a quick way of installing disk images into floppy drives. It was added mainly in recogonition of the fact that some Amiga games came on lots of disks (I used to have an 11-floppy game. I can not tell you how much swapping was involved while playing - no hard disk install in those days!) and that some games, as mentioned, were not written to use more than 1 floppy.
I would suggest there are 3-4 main approaches to using WinUae in a Cab:
1) You only play a handful of classics:
Simply install your favourites to diskswapper, save settings as default, and swap on the fly as required.
2) You want all the games listed nicely in your frontend such as Mamewah.
Annoyingly, could be best to create a seperate cfg for every game you want. There used to be some util on the web that helped set this up, but that was ages ago. This is a pain because some games can require different settings (mainly as the Amiga hardware changed over the years - so technically some games only run on certain Amigas). This is a mammoth task if you have a large adf collection, but also the most FE friendly as Winuae can be run from the command line with no GUI.
3) You want all the games but no config time
Simply wun WinUAE with a gui and use your mouse/trackball to select games etc...
4) Learn about WHDload. (+history lesson)
Ok. Die-hard Amiga people who ended up with (and to this day still use) highend Amigas became annoyed years ago that all there games would not run at all on there systems. Some appalling clever people created a utility that would enable them to run raw diskimages of amiga games directly from the Amiga OS (almost all amiga games could not be run from the OS - they booted themselves with there own custom code). It still required EVERY game to manually patched and hacked to enable it to work correctly with different hardware. It also meant circumnavigating the vast array of copy-protection that was included based around floppy-disk access. This project is still ongoing.
This is relevant because what you can do here is create just one cfg in WinUae to emulate a high-end Amiga that boots to the Amiga OS. You can then have games available (with icons etc...) from the Amiga OS - a bit like an Amiga FE. This has many advantages over the floppy-emulated WinUae approach - all the games (that have been patched) will work under this one WinUae setting, you can quit games with a single key and choose another, the games load lots faster etc...
This will require some reading and setting up - but there are ready downloadable custom AmigaOS images around - google WHDload, Amigainabox, Bloodwych ClassicWB to get you started.
EDIT: Realise I may have over-elaborated and missed your question(!):
I noticed the "diskimage" settings are really the "disk swapper" settings in the GUI, however, I have no idea what the difference between the "disk swapper" and "floppy drives" settings are....... maybe you can help me out.
Floppy drives are the actual devices attached to the Amiga (up to 4). So you can only have 4 images attached to the Amiga at any one time. (Although several games will only yet you use 1 drive, asking you to swap. The more disks a game has, the more likely it will support multiple drives).
Diskswapper is nothing to do with the Amiga, but a WinUAE feature that allows v quick access to 20 floppy images to make disk swapping painless as possible.