@ Orange
I have previously used two 8mb EDO SIMMS on the mobo, but there was no speed difference between that and the ordinary FPM SIMMS. EDO can be used though.
As for the floppy drive, there is a big long thread about that somewhere. The A4KT has a small PCB between the disk drive header and the floppy drive. This presumably enables a partially modified PC drive to read Amiga disks in 880k format. I have found the following in my tests:
1) If I take the PCB out and connect a standard A500 floppy to the header, it works just fine.
2) If I connect a standard PC floppy via the little PCB, I get no joy. This could just have happened because of the two drives I tried though.
3) If I try the A4KT floppy in a PC, it doesn't work at all.
I suppose my best advice to you (if you just want a spare drive) is to get a standard Amiga floppy and when your existing one dies, ditch the PCB and connect the spare directly. Adding a second drive seems to be a ball-ache with finding the right drives or finding someone who sells them.