Great haul, two very nice machines, in very nice configurations. If you just need to transfer files between the two systems, you can get an Apple System/8 Peripheral cable, which is Apple's fancy marketing way to say "serial cable." I just happen to think it's a cool name. You can then connect the machines with localtalk, there's plenty of threads on here about it, and you can ask us too.
Replacement SE floppy should be pretty easy, Duos may be easy to find an HDI24 (I think that's what it was) external floppy for, should hook right up to the minidock.
*Edit: Forgot to mention that the cable attatching the StyleWriter to the Mac is the correct type of serial cable for two-mac networking. If you had phonenet stuff you could hook the stylewriter to both systems at the same time, and do filesharing on them over it.