For powering jet engined aircraft and a few other things I don't know
The jet engines used jet fuel, not gasoline as the 6 main engines did.
yes they are, they are the engines you see on a 747 or even a small Private jet
Steel, titanium and aluminium are all used in jet engines.
For thrust. Engines are used to overcome the drag of the airplane.
Avgas is a common name for fuel used by internal combustion engines in aircraft, while jet fuel is used in jet engines.
There is no actual answer, because a jet is called a jet because it has at least one jet engine.
Jet engines were invented before WW2. They were used in a few late war German fighters.
rocket engines,compared to jet engines
Well yes, assuming if an airplane does not have a jet engine, it would not be called a jet.
Yes. JP5 is primarily used in turbo fan engines, but they are blended for high performance and fuel economy.
An aircraft propelled by jet engines rather than piston engines.
Most modern helicopters use jet engines.