The Fluid Pipes by default input into the tank, but you can right-click the pipe with a Standard Wrench to change it into "pull mode" if you want it to extract fluids from the tank instead. Note: a pipe in "pull mode" needs to be used with another pipe in standard (input) mode. So if you want to pump fluids from a tank to another tank, your pipe needs to be minimum 2 blocks long.
If you break a Fluid Tank, only one source block will remain. So empty your Fluid Tanks before breaking them!
Fluid Tanks will attach to each other if stacked vertically, but not horizontally.Therefore, to store large amounts of fluid without the need for an incredibly tall base, it is recommended to chain them together using Fluid Pipes. One end tank will become an "input" and the other end an "output", so be careful which way round you chain them!