Even if you could 'idle/work' at 1600w, a start up surge, power dip, anything like that could easily exceed 1600w.
And 1600w @100v = 16amps. Can the mains circuit take that? Nowadays many house circuit breakers are 15amp.
Certainly looks like a possible leak.
Put some color in the fluid, attach a white tissue near the area(s) in question and run for a few days. If it is leaking and the tissue stains - you're on to it.
Random thought: Maybe track your start/stop cycles - thermal differences. Maybe thermal...
I think the articles point of additional protection from deliberately releasing faulty product is valid. In simplest of terms, it is deceptive practice, releasing a known flawed product. No different than buying a used car that wont pass an emissions//safety check.
In reality, how do you draw...
What about interference? Maybe it's run past a fluorescent light/transformer or some such noisy device?
Have you tried the cables strung through the house/shop? I am to understand that coiled up (like two PC's side-by-side) can incur problems from induction (more so with cheap cables)...
You are aware that Freenas 8 supports ZFS which is looking more appealing than Raid 5, right?
Hardware wise, this sounds sufficient for a starting point. How far are you looking to grow this? What is the purpose of this? File server or other?
I've got an old Athlon with 4gb, dual gigabit...