Are there any aircraft still in production that use a radial engine?

As an aircraft engineer I have deep concerns over composite and plastics used in aircraft construction. I personally don't think they can possibly last simply because repairing structural damage cannot be 100% guaranteed. Metal and wooden structures are easily repaired or replaced. Splicing and repairing plastic and composites are not so easy and expensive to do. It's often cheaper to buy a new one, which means that the aircraft will be written off rather than anyone having to guarantee any complicated repair. Metal aircraft, however, can easily be repaired given a skilled sheet metal worker and the repairs are often stronger than the original structure.
What worries me about plastic is its tendency to become brittle over time. Most of us have experienced those horrific plastic garden chairs that don't last more than a year before they break. Whilst composite aircraft are clearly of superior quality, I like to see a manufacturer who is prepared to guarantee that his composite (plastic) aircraft will not suffer the same fate over time. There was a plastic glider that broke up in the UK in the late 70s. The owner had painted a dark green band around the rear fuselage just in front of the tail. The differential heat absorption from the sun seriously weakened the area and the tail broke off in flight. No-one can tell yet what we will be confronted with in the future or what people might do to their aircraft and I predict that many will have to be retired when we find out the real lifespan when they start to fail. I personally would need a lot of convincing before I bought one.

From a pilot's point of view, every aircraft comes from the factory with a checklist of things to look at specifically before every flight to ensure airworthiness. It's generally called a walk-around inspection, checking flight controls for security and condition, tire condition, engine for obvious problems. propeller, fuel and oil quantities. and many other things. The walk around also includes checking to ensure all required paperwork is there including weight and balance, airworthiness certificate, aircraft registration, operator's manual. etc. I would also check the log book to verify the transponder check was done within the past 24 months and the annual or 100 hour inspection is current. From an A&P mechanic point of view much the same applies, however I would look much closer at the maintenance logs for engine and airframe.

A true helicopter is one of the more complex flying machines, pound for pound, that there is. And it is much more difficult to fly than a conventional fixed wing aircraft (about six times the workload for the pilot). Having said that, I am going to assume that you are thinking along the lines of "Hey, wouldn't it be great to put some parts together and have my own little helicopter for flying around." And yes, it would.

Specifically, most folks putting together a homebuilt aircraft or helicopter based around an automotive engine seem to like the engines in Subaru Jettas and the like. However, if you can get something like an IO-360 from Lycoming or TCM (perhaps surplus, parted our from an old airplane), that will produce more power per pound. But I warn you, a helicopter takes a LOT more than just hooking an engine to a rotor.

Probably a lot more practical - look into some of the ultralights. If you really want a helicopter-like vehicle, consider a gyrocopter. A heck of a lot simpler to build. With an "pre-rotate" feature, they can almost take off from a standing start, and have a very short landing roll. Look into a magazine called "Kitplane" for some ideas, and join EAA (Experimental Aircraft Association). Good luck, and fly safe.

here ya go...
http://www.explainthatstuff.com/jetengine.html
tis physics.

Most headset and aircraft mics have noise cancelling because between engine and wind noise it would be difficult to understand the pilot without it. To use the noise cancelling mic it must be very near the lips

no but the flight engineer moniters fuel and electrical use hydraulic levels and apu operation

Its easier to control the airplane with that balance, a twin like that would be easier than a single for the same reason that the prop rotation makes the plane easier to turn to one side than the other.

The DC10 was an excellent aircraft, with a long and successful service history. They are still flying in many countries, and in the US you see lots of them with the freight haulers.
There were, unfortunately, a few (very few) high profile crashes - which is probably what you refer to. The infamous "engine drop" issue was bad maintenance - not a problem with the aircraft design. And the Sioux City crash (pilot Al Haynes) was caused by a truly unlikely event that simply proves that even low odds can happen. [An uncontained blade failure on the #2 engine ejected "just right" (or just wrong) and cut the one small spot where all the control surface hydraulic lines came briefly together.]
The reason that DC10's are no longer in primary service is attributable to two things:
1. Older fuel hungry engines (3 of them), compared to the more fuel efficient twin engine design. And the changes to ETOPS regulations that now allow twin engine airliners to fly trans-ocean.
2. Certification of the aircraft with a three-person crew, in stead of the cheaper two-person flight crew common now. [The freight haulers get around this by cross training the loadmaster (only needed on the ground) to also be the flight engineer (only needed in the air).