for the pool its great
you can use the pool to put different sounds in on a per step basis
try this:
first select some drum sounds put them in the pool
go into step mode hold a step turn the selection wheel
this opens the pool and you can select the sound you like to use on that step
reminder you can only select sounds on a per step basis that are in the pool
I use my Library for most leads and the pool for drum parts and such that easily fit on one track or more
hope this helps