gaz,
It does depend on fleet, I'm on the Hawker 800XPC and I'm averaging 400 hours or so per year. The large cabin fleets do more hours.
Icehouse,
Not exactly sure what you mean by the question. I wouldn't plan on overnighting in Manchester as a regular thing. My gateway's Luton, I do operate through here a lot. But Luton is one of NJE's more busiest destinations. You're paired with a crew and aircraft for the 6 days. Where you'll go is up to Scheduling. (sometimes you'll crew or aircraft swap but it's not the way it's rostered)
Many of these answers can be found on the NetJets Europe website or in the bizjet forum.