Just a note on this point - yes!
Longer containers have connecting points at the standard 40' length, so 40'-53' containers can pretty much be stacked in any combination.
Containers do not have connecting points in the center so 20' containers can not be stacked on top of longer containers and will always be in the bottom of wells.
There *may* be some slight compatibility issues here and there but most brands *should* work together if they're dimensionally accurate and any issues should be very minor and easily tweaked. Stay away from Con-Cor containers though as for some unknown reason whoever designed them made them with pegs that stick *up* on top of the containers - which both looks stupid and makes them incompatible with other brands.