Uncle joe's... m.b.
Regrading your question about the RPM, as I said earlier, if you have the collective fully down, during an established glide (power off) at 65 KIAS, you should not have to worry about the RPM being to low and not recovering.
I have plenty of experience in both the R22/R44 and as a normal weight pilot- no trouble. If you cannot contain the RPM, then there has to be something else wrong.
The above is based though on an immediate entry meaning collective fully down instantaneoulsy. You don't have the inirtia of a Bell 212 rotor and if you don't lower the collective immediately, it is quite possible for the RPM to droop of and only recover very, very slowely. Still, it should recover if all is OK with the rotor rigging.
About practicing autos, by no means would I like to discourage anybody from practicing emergency procedures. However, having trained many people in the R22 and R44, amongst them, like yourself, very experienced fixed wing pilots, I would just strongly urge you to think about it twice in an R22 especially at the early stage in helicopters you are in.
As I said, it is a great training helicopter, never the less very unforgiving.
Training autos with an instructor in the R22 can be much more rewarding then solo. If you have passed your checkride I guess you will stand a fair chance living through an auto.
However, only continuous instruction to an advanced level will teach you how to successfully walk away, pick up another machine and go flying again.
And the thing about the R22 also is that establishing the glide isn't the hardest. Most hard landings occur during power recoveries, due to the fact that people overcontrol the aircraft, have difficulties coming out of turns resulting in generally low RPM, the speed is being bled off and there you go....
I hope you understand my scenario- it is absolutely not a critique on your pilot judgement, just a suggestion. Just like I wouldn't go out in a fixed wing during my first solo and practice steep spirals.