Throttle control not an issue.
I have been a bike rider for many years and throttle action was not a concern.
You will take a little getting used to it. You will adapt pretty easily.
Safe auto's are relevant to your airspeed,altitude & how strong the wind is to assist you in the flare.
The higher your airspeed the lower (to a degree) your auto can be.
Its all about how much time you have to react & giving you options to set it down with out balling it up.
In a 300/22
Auto's are generally practiced from about 600ft AGL / 70 knots but can be done higher at less airspeeds or lower at higher airspeeds.
Hover autos (either stationary or moving at a slow walking pace, are generally practiced at 3-5 feet.
Different helicopters have different performance characteristics.
HF