hello, I have the above mentioned rifle also,
1. Don't really know how accurate the gauge is
2. I fill mine up when it drops to 100bar, top it up to around 180
3. I use AA diablo fields or JSB exact,thats for everything
4. Only used the other air arms, hunters, don't rate them compared to the fields.
5. Mine has been a real good reliable gun, going in for service next week, had it from new(jan 2007) oh, just for cosmetics, I would remove silencer before attatching filling adaptor.