If this is one vs one and ur opponent is either terran or protoss i dont think you will need a bunker its a waste and it slows you down. Even if it was a 2v2 teching like that is a real no no if you were going against gosu players. If u manage to pull it off good stuff but also pulling this off requires a crap load of micro.

You dont really need to quickly build another depot that early (unless your playing it safe) i rather use that 100mineral to building a factory and quickly get moto bike depends what opponent is going to do.

Well a pretty good strat otherwise it seems you like to play it safe. Also it looks as if your a 2v2 player since your building rines and bunker probably to stop zergling attack. When your first supply depot is finished that SCV should explore while another one comes to build a rack.