Here goes:
1. Yes, very.
2. That's what simulators are for.
3. Personally, no but there is scope to do so if as in your case the unexpected happens! Are you sure the rapid loss of Nr was representative of the real aircraft? I have used a simulator in the past where this was not the case, the Nr loss was so great when practicing double engine failures that we had to inhibit the loss of Nr protocol.
4. There is a school of thought that all LPC/OPC flights should be done in the sim but I think that at least one check every couple of years in the real aircraft helps to keep in touch with the real world.
Might I just add that one of my pet hates is when I hear pilots say "this is what happens in the sim so it must be real"
The simulator is only as good as the data that was used to replicate the flight characteristics and the engineers who put the thing together. I have yet to find a
helicopter simulator which is fully representative throughout the whole flight envelope - they're getting closer all the time but not quite there yet.