Hi,
I actually have the kn7 not the kn26, but a lot of the functions are the same.

if you're only going to save audio files to your laptop, use the Audio Recorder software that I assume came with the kn2600 ( unless you have some better software program)

A card reader is handy (as it's faster than usb) for backing up your sd card files to computer.
(Again I'm assuming that kn26 has the same functions). If you're not planning to use audio on your sd card, then any SD card reader/writer should work for backing up purposes. I bought a couple of cheap ones on ebay a while back for $14 USD plus postage
but they don't work with audio files ( mp3's) on the kn ( I had to buy the Panasonic Kit for that)

What midi questions did you have?

Maybe someone can help.

best wishes
Rikki