a) Let's start with the emergency situation. Engine goes and you are about a 1000 feet off the ground. Result is that you have about 45 seconds before ground contact. A gyro will typically descend at about 1200 to 1500 ft/min. A smart pilot will fly at an altitude that will allow his safe glide to a landing spot, therefore if over a forest area, 10,000 feet may not be enough. I have found that guys DO NOT always practice their forced landings and emergency drill or plan their routs over safe areas at a reasonable height. Low and slow is also a bad combination as that extra 10 mph could just take you to a safe place. Low flying and wires seem to go hand in hand.
Dropping a gyro can safely be done from about a meter above the ground provided that the gyro remains upright. This will not shorten your spine. Above a meter, the chances of remaining upright could prove difficult as the gyro can bouce back up again, resulting in loss of control which is turn can result in extensive damage. Higher than 2 meters with a descent rate of 1000 ft/min, you might find yourself becoming a bit shorter due to the impact. It all depends on the vertical impact speed.
Dangerous practices are allowing yourself to end up behind the curve at too low an altitude to recover. This means that you are using all your power and your airspeed is decreasing (stick full back) and you ARE GOING DOWN!!!
Next dangerous practice is to do "shoot ups" where you actually start feeling weightless in a gyro. This results in the blade loosing RPM, thus becoming unloaded and ........
Most modern gyros in the RSA do not really sucumb to PIO but this is not to say that it cannot happen. I have personally tried to put a Magni into PIO and found that it is pretty positively stable. A new student is inclined to either under control or over control. Over control can bring about PIO.
Aerobatics in a gyro are out - plain and simple - no loops, rolls etc. If you have a death wish, DO THEM!!!!!
Your question about mountains etc is actually quite simple - DO NOT FLY ANYTHING ABOVE YOUR OWN LIMITATION. This means that if you have just obtained your gyro licence, you are still learning to fly. Rather get your basics sorted first, then go to a competant instructor that HAS flown mountains and let him take you through it. I suggest that you have at least 100 hours solo before trying to fly mountains with your instructor. Talk to Len. He has a course going in exactly that.
Flying outside the gyro's scope or envelope (as well as your own) is another danger area and this applies to all aircraft. This includes flying in Hot, High and Humid conditions, overloading, short horrible runways etc. Simple rule of thumb - NOT SURE? DON'T!!!
Trying to climb with a gyro and runway already behind you is the result of either a downdraft, overload, sick engine, or trying to climb on the back of the curve. I have always taught my students that you land 15 degrees either side of the extended center line dead ahead of you. Turning back, in this case, may aggrevate the situation.
The gyro in general is a very safe aircraft. However it does have rules and if they are not obeyed, you pay the price, one way or another.
Never loose respect for your gyro or the weather. Gyros can handle serious stuff, but cloud dancing is out - there is very hard stuff hidden i clouds (called terrain) and that has killed many a pilot.
b) Going back to my earlier post, you will notice that I gave something of the rate of descent of a gyro ie 1200-1500 ft/min.
At a 1000 feet AGL you have about 45 seconds. At 500 feet you will have about 22 seconds, at 50 feet AGL, you have about 2 seconds. Flying low over "hostile terrain" is in itself not a good idea and even in PPL this fact is pointed out.This in itself should answer the question of low level flights and what I personally now think of them. Let me be quite honest with you - nobody flew lower than what I did on long trips. It took the death of a friend, (and ex student), to give me a wake up call after many years of low flying. You think you are bullet proof until something happens, and that is where the wheels pop off.
Why do pilots then do it? Because it produces a "rush of speed" and some sort of adrenalin rush, not forgetting that ego thing. Is it worth it? No!!!
Again I also come back to the properties of the aircraft itself - you are trying to push the limit on the aircraft. There is no way that you will gain much height when the engine goes. The engine will start "dying" on you and before you know it, you would have lost altitude anyway. It is very seldom that one will find the engine producing full power and then suddenly stop. My engine went, after putting a con rod through the block, milling 4 cylinder skirts to pieces, and producing millions of tiny particles that went all over the engine to really make matters worse. Yet that engine gradually lost power and only finally died when the wheels touched down on a safe landing. Even an out of fuel engine stop will give a warning. I often tell my students that a gyro has a glide ratio of a falling block of flats!!!
Going back to your question about collective control on a chopper as opposed to a gyro. You are right - there is no collective on a gyro. Go back to your gyro instructor and if he knows what he is doing, he will show you how to convert height into speed, using the extra speed at the right moment to convert this into rotor blade energy ie speed up the blade and thus produce more lift just before touch down and you should not have to drop more than half a meter, and thus a soft landing. Crash and burn is not the end result. Please do not try this on your own unless you are completely trained by a competant instructor, as judgement is everything in this case and I do not want people going out and bending gyros because they have read this. GET THE TRAINING!!!!!!
A gyro put down in this way, should have very little (if any) forward speed and the vertical speed is greatly reduced. This means that the area that is landed in, as long as it is reasonably flat, will be a safe area to land in and remain intact. How you get your gyro out of there is another issue.
As far as crash and burn is concerned. Helicopters and gyros have to hold their fuel somewhere in the fuselage, while fixed wing planes keep fuel in the wings. It is a given fact (and millions have been spent on this issue) that choppers and gyros, when toppled, do often spill fuel, which, when this fuel comes into contact with a hot exhaust, can cause combustion and start a fire. This again is a good reason to fly high, and, when the engine goes, will give the exhaust time to cool down and thus prevent a fire.
Regarding your idea of saving yourself and not the gyro is a pretty common statement among pilots and this is also drilled into them. I say that if the gyro completes a safe emergency landing, remaining intact, it will follow that the pilot (and pax) will be intact. However, if the gyro is toppled for any reason, then the chances are that the pilot (and pax) could get injured. Even in a chopper, you have a "dead man's" altitude, which means that if the engine goes and you are below that altitude, you are going to get hurt. The collective is not a means to save all.