Mass Media Storage basically turns your phone into a flash drive on your pc when you plug your phone into it with the USB cord. I set it to on because I like being able to drag and drop things onto my phone as its faster that way ie: music mps's, videos, pics, etc etc. The only time files are not accessible is when you have it plugged into your pc, you just cant access the media folder from your phone until you unplug it from the pc. Then all will be as normal. If you plan to add things to your media card, I would suggest turning it on as it makes life much easier. But its all relative in how you like to do things and what you are used to.
Not sure on the brickbreaker thing, have never had that issue on mine. Only thing i could think is that your memory may be low and you need a battery pull.
The very existence of flamethrowers proves that sometime, somewhere, some1 said 2 thmslvs "U knw, I really want 2 set those people over there on fire, but I'm just not close engh to get the job done".