So, to get it straight:

1) The NIT doesn't have VGA/DVI out.
2) The NIT doesn't have ability to function as NAS.
3) The NIT doesn't have ability to function as WiFi AP.

I believe there are already many, small embedded projects out there which allow one to build (or buy) a device which does have these 3 capabilities. You can buy a cheap, energy efficient motherbord from AMD, Intel, or VIA (or ARM or POWER) right now. The question is: whats the best price/performance.

As you point out, a laptop serves this purpose. A nettop serves this purpose as well. Option 2 I disagree with because this requires a HDD which eats W for breakfast (30W to spin up, 9W in use). A 16 GB SD card can contain your data just fine if you plan well what to put on it. The same would be true for a NAS (or laptop/nettop) though, it could just hold more data.