Yes. In case you have multiple Macs, be sure to open the database in only one instance of DEVONthink at a time. Speed and response will depend on your network, obviously. Over here, I use power liner ethernet, which works well and faster than WiFi.
Just my two cents but I would i[/i] stay away from using an NAS since they use a non-standard filesystem (often ext3) which keeps it from being indexable by Spotlight. In my opinion, losing Spotlight functionality is too great a loss.
Yes, I would have only one copy. Power line ethernet is a good idea, but if I understand, it would mean that DTPO data would be available only within the house. I would want it accessible from office and on the road.
750GB is available but very expensive.
Didn’t know about Spotlight and NAS. That’s something to bear in mind, not only for DTOP but also for iTunes etc…