Pull over when it is safe to do so, shut the vehicle off and have the vehicle towed to a trusted garage for an evaluation. Driving it when that hot may cause damage, serious damage to engine.
I assume you mean "When your hot water needle does NOT work." Thermostat.
could it be the thermostat or the fan itself?
Could be a vacuum leak.
As engine has to work hard and engine RPM are high its temperature rises and water pump also works faster and hot water reaches temperature sensor fast and suddenly needle goes up.
The eye of the needle.
No, the needle is the same as any piercing.
No. Too hot is when the needle gets about 3/4 over on typical guages, sometimes it's marked in red, sometimes not. Either way, there should be a marked line around the 3/4 position on the guage, past that is not good.
Multiple problems could contribute but I would need more details such as does it turn off on it's own or when you turn it off the needle jumps then the car stops running.
You could have a bad thermostat, a blown head gasket, a cracked head.
In a radiator, the fluids get really hot, when things get hot they expand and then they have to go somewhere, the fluid goes into an overflow.
If the speedometer needle is going crazy and not working properly, it is probably the speedometer mechanism that needs to be replaced. It could also mean the vehicle is having a transmission slippage problem if the needle is bouncing back and forth.
The machine that has a needle that goes from side to side is an overlock serger. It is used to prevent fabric from fraying.