get many different signals through one wire
what you want is multiplexer, there are many different types of muliplexing

time division and frequency division are two common types of multiplexing.

you appear to be describing time division mulplexing in your description, 

It seems to me you really only need a USB extender and a USB hub on the end to connect your devices to, USB uses a complicated form of time division multiplexing internally.

hoever if you want to build your own system you want to serialize the data at the source end an deserialize is at the other end.  there are SERDES chips designed to do this sort of stuff but ther are likely a million times too fast.

for analogue signals like potentiometers you might find something useful in radio control encoders, these encode potentiometers to a time division multiplexed PWM signal, you can probably decode it using a sound-card and specialized software.