Chr, I agree with ShyTorque, you asked too much from your engine. That was not an aerodynamic problem of the rotor.
Let me paint you a picture. In the first situation you said you had very little tail wind. What, 10 kts? 15? Anyway while you initiate your turn and decelerate you fall out of translational lift (the shudder). Depending on the direction of the turn, you might use even more power because your tail rotor wants power, too. And now you are in a situation where you need more power than you have. Ergo, NR drops. The thing is, you fly by a ground track and your brain tells you that you still move fast enough for translational lift, but your rotor does not care about the ground track. The tailwind made your rotor loose translational lift earlier as you anticipated. And you are in a turn, therefore your load factor increased. You are not the first one that falls into that trap.
In the second scenario you also asked too much from the engine. Again, that has very little to do with the aerodynamics of the rotor, but with power management. If you need power in the flare to stop the sink rate, you probably did something wrong earlier. Initiated the flare too late, for example.
There is nothing gained from flying spectacular if you are not paid by Red Bull to do so. If you do that in front of passengers you are going to pick up, at least half of them will be scared. The other half think it is normal to fly like that. Nobody will be impressed. Would I stand there I would probably think that I go flying with somebody else. Or tell you to move over and let me fly. If you want to impress, try to fly with finesse. Try that for once. Pick up the ship to a two feet hover on a runway and now accelerate the ship very gently to translational lift without pulling more power and continue until you are at your cruise altitude and speed. Be careful not to touch the ground. You will be amazed, how little of height you loose, if you do that very gently. Once you find out how all that works, you can fly a whole circuit without changing the power setting. Coming down takes a bit cheating (pull carb heat for example), but it is fun. Prepares for a stuck collective. Be careful with slipping, because some helicopters with their high CG, will bite back if slipped too aggressively. Stay in the limits. If the handbook says no slipping, no slipping it is. But once you are behind the power curve, carefully reducing speed and altitude, you can come out of translational lift and to a hover just with the cyclic and pedals. Takes a while but I think it is very gratifying to fly like that. It gives you a much better feeling for the ship. You are mentally always ahead of the ship and gives you training for situations you do need finesse. If you are not experienced enough, ask a CFI to fly with you. Flying gently and with finesse is much safer. Many of us have landed in spots where we could not hover. It is not something we should do and if you crash, they will blame you for that. But coming in to a spot like that, which might be a small platform where you will not get a lot of ground effect, with your power almost maxed out, asks to be very gently. An aggressive flare and the subsequent pull on the collective will end in a more or less devastating crash.
And should you have your own helicopter, flying with finesse saves money in the long run. If you rent, finesse will impress the owner. Helicopters are not aerobatic aircrafts. They are all relatively flimsy. Any spectacular flying will cost you more beans from the jar and things will break earlier. Red Bulls maintenance requirements are eye watering for their aerobatic ships.