Hi Jamie,
The easiest bit to answer is your Final Cut program question. If you have two different licences for FCP7 then you can run both at the same time. If you’re trying to use the same licence it quits on start up same as if you try and do it over a network (I’ve tried the same thing).
As for NAS drives, the company I work for is looking to do the same thing so i’ve been doing a lot of research. That drive you’re looking at is a good option but the other one I would recommend taking a look at is DROBO. Don’t pay too much attention to the bad reviews as most of them were posted before 2009 and they’ve really sorted out the stability and customer service issues. The main advantage that I can see is that you can mix and match your hard drive sizes to keep it as flexible as you want (for example in a 4 bay you could have 3x3TB and 1x1TB drive). I know a lot of the larger post houses that use FCP use the server version but the 4 and 5 bay versions are supposed to run really well across ethernet. I will admit that I haven’t tested this personally so it’s only word of mouth at the moment.
But to a certain extent it’s up to personal preference. A lot of my engineering friends tell me I should build my own as it will be cheaper but I don’t know about you: my server/computer building skills are a little bit behind!
If you make a decision, let me know how it goes! I’d be interested to hear 🙂
Good luck,
Drew