The fuel system is quite similar to the BN2. The tips can only be transferred into the mains. The wing engines can feed from either main, the rear engine can be selected to feed from either main or "both". I only had 1 fuel Tx pump go U/s, but from memory they are supposed to be inspected/cleaned every 100 hours, so try to ensure this is done.
BN3 is probably even slower in roll than the BN2 and a bit heavier in pitch. It is a bit faster 135-140 TAS, I found 100kg of GW made around 1 knot difference of TAS. It will get up and boogie at light GW and a cold day. Main trick I found was the pilot's eye height on landing, you are still really high when the mains touch down. Also on landing, I found (when heavy) reducing power on the outboard engines but leaving a smidgeon on the centre produced nice smooth landings. Seemed a bit easier to land than the BN2 once the height thing is mastered.
Ground handling pretty easy with the nose wheel able to unlock and castor- but watch the wing tips. They stick out even further than on the BN2 and you can't see them.
Very cold aircraft to fly in winter, you will probably find it doesn't have a heater. rear engine seems to be more susceptible to plug fouling. Also stuggles to climb when full on a hot day, but runway performance is still pretty good.
Just my rambling thoughts. Feel free to email for more info.