Probably an alternator.
yes .. if the car is in drive and u put it in reverse.... bye bye gears
if an automatic transmission is grinding in reverse it is probably an internal failure. The car will probably need a good mechanic who specializes in transmissions to look at it to be sure. I have seen some cars with a simple linkage problem do this...but its unlikely.
If you mean each time you engage car in any gear forward or reverse & it immediately stalls - you have a bad torque converter. Start engine, put foot on brake, put car in NEUTRAL, if it DOES NOT stall, but it does stall if you repeat this test when you put car in drive or reverse = bad torque converter - It's called a "stall test"
Put it into reverse when moving rapidly forward.
Nothing if you are sitting still. However if you are moving forward and it is an older car, you may be replacing a transmission. Most if not all cars today with and automatic trasnmission have a failsafe to prevent going into reverse while going forward.
well it depends if your wanting to go backwards then you put the car in reverse . or if your wanting to stop then you put the car on neutral.
You put the automatic in neutral, or put a dolly under the drive wheels.
Low Transmission fluid
the car goes back
Get it rebuilt
The car might have an automatic cut off to either disengage the transmission or cut off the engine. Otherwise you will rip apart the transmission.