yup, the clockport adapter plugs into the CPU socket on the mainboard.
the accelerator would plug into the CPU socket on the clockport adapter, and the old 68000 chip would plug into the 68k socket on the accelerator if you need it for backwards compatability.
however, you may find that stack of hardware means your keyboard doesn't fit right anymore ;-)
plugging a subway into the clockport adapter will give you USB on your A500 for keyboards, mice, usb memory sticks, CD drives, hard disks, etc. etc. and even USB>Ethernet adapters.
although, i don't know of any drivers for USB>Wifi adapters for the amiga, and there is something up with the hard/software of the subway and USB drivers for USB>LAN adapters (using the pegasus2 chipset - in my experience) that causes massive amounts of CPU interepts.
this results in slow screen redraws, jerky mouse movement, and transfer rates no better than a direct serial to serial connection. or even parallel to parallel using the old 68000 gives you 20KB/s...
it might be something up with my hardware config, but to be honest, since i can't figure it out, i've given up with my a500... :-(