this one has a giant keep-out area at the nfc chip, or is it just for tinkering?
edit:
i think in future OH development it is a really good idea to make an eagle -or whatever- file for the NFC chip, basicly a giant keep-out area on both sides and a silkscreen with where to stick it. maybe a giant sticky with tips, hints, practical stuff and files?
I'm not (yet) in hardware development development but is it possible to somehow connect a serial device (ps/2 powered, 5v) to your interface?
Afaik, i2c is not compatible ps/2. You'll need a converter (I did a fast search, didn't find any simple solution) or select a device which supports i2c. Another solution is to use SPI device if i2c supported devices aren't available and use some converter chip to make it work with i2c.