I was curious that would the spell "bestow curse" stack with any other curses?
Would it stack if two "bestow curses" were to be casted on one given target?
Is it the same ruling for "greater bestow curse"?
Yes, they stack, but only with curses from different sources and spells.
In most cases, modifiers to a given check or roll stack (combine for a cumulative effect) if they come from different sources and have different types (or no type at all), but do not stack if they have the same type or come from the same source (such as the same spell cast twice in succession). — "Modifiers, Stacking", d20SRD.org
So this means that: