Firstly I would say refer to the B737 Flight crew training manual.
Boeing allow a manuovre margin in calculating buffet limits. This margin is usually .3G......ie allows for a .3G over and above an expected 1G manourvre. This (if level flight and constant speed is maintained) coresponds to 40 degrees AOB. So you are correct in saying you have bank angle protection in the speed regime up to 40 degrees.(commonly called the yellow hockey stick) This is not to say that it is normal procedure to use it. Deviations (or I think you are refering to speed trend indications on the PFD) are to be expected as the trend indicates a dynamic parameter. That is to say that the input data is constantly changeing. Remember this trend vector indicates expected speed in 10 seconds if flight parameters remain unchanged. So what I'm saying is, small trend indications around the "Flap Up" indicator on the speed tape are expected in any aircraft and are normal. Sustained decreasing or increasing trend indications on the PFD must be dealt with appropriately by the pilot. As for you noise abatement concerns. The NADP will end as marked on the plate. Hope this helps. Happy to accept the obvious barrage that will folllow........my 2 cents worth.