Clock, Rear Defogger And Speaker Problems

HELLO, I HAVE A TOYOTA AVALON 98, I REALLY NEED HELP WITH MY CLOCK, YESTERDAY, I CHECKED COUPLE OF FUSES IN THE CAR BECAUSE MY ANTI-THEFT WOULDN'T WORK. THIS MORNING AS I WAS TRYING TO GO TO WORK, I NOTICED THE CLOCK SHOWING "1:00", AND WAS VERY FAINT AND BLINKING LIKE WHAT IS ABOUT TO GO OFF AT ANY SECOND. nWAYZ I DROVE TO WORK AND UNPLUGGED THE NEGATIVE TERMINAL ON MY BATTERY HEAD AND REPLACED IT.THE CLOCK REFUSED TO COME ON AGAIN OR EVEN FLICKER. ALSO, MY REAR WINDOW DEFROSTER WON'T WORK, BUT WHEN I HIT THE SWITCH I HEAR A NOISE WHICH INDICATES ITS ON, BUT WOULDN'T DEFOG THE REAR WINDOW. ANOTHER HELP, I AM TRYING TO CHANGE THE REAR MOUNTED SPEAKERS, AND WOULD WANT TO KNOW WHAT SIZE TO GET. I TRIED CHANGING IT BEFORE BY GETTING ONE FROM A JUNK YARD, IT WASN'T GOOD ENOUGH SO I DONT KNOW IF I COULD GET ONE OF THE SAME SIZE FROM THE SHOP. I WOULD LIKE TO KNOW WHAT IS THE SIZE AND THAT OF THE FRONT DOOR SPEAKERS. THANKS TO ANYONE WHO CAN HELP ME WITH THESE PROBLEMS...