Cessna 172 Skyhawk (G1000) Slow at cruise

  1. What about 1000 feet altitude? In MSFS I have 90 knots and dropping at 2100 RPM. What airspeed shall I expect at 2100 RPM, clean configuration at 50%fuel tanks + 2 standard pilots? For fully-loaded C-172S, according to POH, I expect at sea level 75% power 114 knots, at 4000 feet 119 knots, and at 8000 124 knots. At 65% - 108/112/117 accordingly and at 55% - 101/104/107.
  2. When I transit from climb to horizontal flight (after take-off at pattern altitude 1000 feet, for example) and accelerate to 100 knots and reduce RPM to 2100 my RPM is not rising to 2200-2300, it drops often or rises to 2120-2130. Is this OK or my expectations (rising from 2100 to 2200-2300) are wrong and my memory is wrong?