The Wright brothers flew the first powered piloted flight in 1903. If you mean anything that was man made like a glider or balloon then that happened many years earlier. The exact date is unknown but it could have been in hundreds of years earlier.
No such thing-we are all just human and can only fly with aid of mechanical devices.
NASA used an F-8C for its Digital Fly-by-Wire Program-the first digital fly-by-wire aircraft to operate without a mechanical backup system.
Only with mechanical help
Some do and have.
he invented the first mechanical calculator.
There is no such thing as the 'rate of mechanical power', because power itself is a rate. There's also no such thing as 'mechanical' power as power is a rate, not something that is tangible.
If you mean "the first plane that had a motor and propeller, and could fly" then it was the Wright Brothers. If you're not worried about the thing being able to fly, there were LOTS of guys who made propeller planes that couldn't fly.
By simple mechanical mixing.
As far as I know, there is no such thing as "mechanical heat energy"; there is mechanical energy, and there is heat energy.
No. There are many other forms of mechanical energy.
A sheep, chicken, and a duck all at the same time