Generally I use half flap (or a smaller percentage of flap) for take off and climb out. On my jet half flap gives a comfortable amount of 'up trim' so to speak & this equates to a nice climb rate without elevator input.
On landing I slow the model, drop the wheels then full flap on the downwind leg on a rectangular approach. Then it's back up on the throttle to drag the model to the strip using the throttle to control the rate of decent & the elevator to control the pitch angle.
It's a bit of a different technique to rag & bone aeroplanes but that's what you do with heavier, flapped aircraft.
45 degrees seems like a lot when you think of aileron deflection.
Not unusual at all, many use more, a Spitfire uses 90 deg.
Pitch change on models is usual with flaps, either up or down, this can be mixed out with elevator mixing but the pitch change will probably vary with speed so it's hard to get a setting to suit all speeds. - John.