For your first question, I don't know the plot of the "dead man's curve" for models. The full size helis, each different type has that info in the flight manual. It will differ with different models also. Sometimes I feel tempted to experiment, but I haven't given in yet.

Regarding the second question, typically around -2 or -3 degrees is what you would use. It's about the same for full size helis.

But, as with full size helis, if you're hovering near the ground you don't go negative. You might make your first auto from a 2 foot hover, where you don't have to do anything other than increase collective to land soft. It wouldn't be bad if you didn't do anything. From that height you can take your time. From a 4 foot hover you won't have as much time to mess around.

If you're motoring through the sky when you drop power you want to go negative (-3 deg) right away and hold that and maintain forward speed. When you're around 6 feet pull the nose up enough to trade off speed for a slow descent. Be sure to get it level before the tail hits the ground. As you level the skids come up to hover pitch. From there it's like a hovering auto. If you still have forward speed be sure to keep control of the heading. You don't want to hit the ground going sideways and you don't want to burn up all your rpm trying to get fully stopped. If the ground is smooth it doesn't hurt anything to land with a bit of forward speed if the heli is heading in the direction it's traveling.