For the overflow, you can buy them with those U tubes going from an internal to external container or you can do a DIY overflow out of PVC if you are handy.
Either way you need a return pump of some kind.
This is the way I did them. I may have already posted but my memory is bad.
DIY Overflow
Either way you need a return pump of some kind.
This is the way I did them. I may have already posted but my memory is bad.
DIY Overflow