As long as you allow it - it will continue. If he gets his way when he whines and cries...there is no reason for him to stop whining and crying. PERIOD.
Stop coddling him. he's EIGHT YEARS OLD - let him set his clothes out by himself the night before school - then he CANNOT whine about what he has to wear - he selected it.
Homework? He has 15 minutes after school for snack and play - then after that - it's HOMEWORK. No tv, game boy, XBOX, Wii or ANYTHING until his homework is done. It should not take more than one hour to get homework done. If he can get up and complain to you about it - then he is manipulating you and you are allowing it. Set a timer if you have to. If his homework isn't done before the timer goes off - he can go to bed. YOU are the Mommy - YOU set the rules and boundaries NOT the child.
It is NOT your responsibility to make your son happy. I know that sounds cold, but really, he has to adjust to life as well. he will NOT always get his way.
When he whines - tell him you cannot hear him through the whining. And IGNORE any tantrums that he throws. If you said NO to something - it STAYS no - no matter how loud he screams, whines or cries. No means No. PERIOD.
He has been allowed to rule the roost since you let him whine and cry. You don't have to make anything up to him and give him his way - it's like you are guilty of something and making it up to him....I may be totally off - but really - at 8 years old, he can set out his own clothes. he CAN do his homework.
The smallest things trigger him because you are trying to make his world perfect and safe and all these other things. STOP! Tell him what you expect. Do NOT allow him to whine when he doesn't get his way. Show him what you expect - if you are going to school too - sit down and do your homework then too. Lead by example.
Stop allowing him to whine.
Stop trying to make it easy for him - life is not easy.
Stop trying to do things for him. Let HIM do it.
YOU CAN DO THIS!!