I need to calculate a set of minimum bounding boxes for a polygon. Id est having a complex polygon I want to envelope it with a set of small boxes instead of a big one.
I suppose that what you want to do is to create a polygon grid and select all grid cells which intersects the polygon geometry.
If I am right, please reformat your question because it does not make sense as is stands now. By definition a geometry has exactly one bounding box or minimum bounding rectangle as it is also called.
Most spatial software will allow you to find a bounding box. Using max/min coordinates in lon/lat directions will also make it easy to establish corner coordinates for a bounding box. You will find the answer to this particular challenge using python in QGIS here.
As for splitting it you could use any set of polygons. You could create a fishnet of your choice or use an existing one. Then do an intersect between your bounding box and the fishnet/polygon set you are using.