Yes they are still being used but they are not popular. That answer is true for military airplanes but for civilian airplanes propeller driven airplanes are the MOST flown and more of them are being manufactured than jet planes.
everything any other plane does
no, there were not jet planes in WW1. However, there were propeller powered biplanes that were used to a great extent in reconnociance.
There are three different types of gases used there is type A which is used for commercial airliners, type B which is used for smaller, and type C which is used for propeller driven planes specifically water planes. While the above may be true, jet fuel is essentially kerosene.
automobile propeller shaft material
Propeller driven piston internal combustion engines. Similar to the one in your car, except planes usually used either radial or rotary engines, both of which have the cylinders arranged in a circle and typically have a multiple of 9 cylinders.
Sweeping minefeilds and drone spy planes
Pioneered in WW1, the wooden framed propeller driven airplanes were covered with cloth and had two or three wings. They were used originally as reconnaissance aircraft, and evolved into shooting at each other in air to air combat (dog-fighting).
Early aircraft propellers were made out of solid or laminated wood with later, more modern propellers being constructed from metal. The latest propeller designs are made out of composite materials.
The one that came with it. If you're buying a used ultralight with no propeller and the manufacturer is still in business, contact them for a replacement. If they're out of business, do a web search for ultralight aircraft forums, join one and ask the membership what to get.
To power vehicles, for example, it is used as rocket fuel to power rockets and planes.
A jet plane has "thrust reversers" which effectively fold the jet engine's thrust around to the front, and these are used at landing to slow the plane down quickly. They are not used, as far as I know, to push the plane backwards from a standing stop; I suspect they are not efficient enough to do that. Jet planes are usually "pushed back" from the gate by specially designed trucks. Propeller planes similarly have a mechanism for turning the propeller blades backward, to slow them down on landing; so I believe they can generally roll themselves backwards on the ground if required. Neither type of plane can fly backwards; the aerodynamics would be all wrong.
Being part of England, they flew British planes.