The first drawing is just a standard symbol for a Pot - the two legs and a wiper. As the Wiper moves the resistance between on leg and the wiper decreaces and the resistance between the wiper and the other leg decreaces. The Center drawing is a standard pot set up to be a variable resistor. The reason the wiper is connected to one of the legs is to set the fail state. This connection eleminates the resistance of the lower part of the pot resistor causing the whole thing to give the resistance of the top part. The fail state, if the wiper fails and disconneccts from the resistor, can be set either to a short or full resistance instead of a floating undefined condition without this type of connection.
The last drawing I havent seen before but it looks like a resistor with a bunch of taps. Like a pot but each tap is evenly spaced giving equal resistance between each step.
The pot with 10 legs is a bit strange It might be a digital encoder instead of a pot. A little testing with your multimeter should help figure our what each pin is doing.
Brent