The highest I've heard of is yotta and lowest is yocto
There is "googol" and "googolplex".
Googol = * 10^100, ten to the power of 100
Googolplex = * 10^(10^100), ten to the power of 1 googol
These extremely large metric/SI prefixes are not often used.
No there are not, nor has there every been.