Re: I got some players!!!.... But I need some help..
To avoid the munchkinism, don't let the players write up munchkin characters. Don't let them min-max, and explain to them that if they buy a huge high DEX it won't prevent them from ever being hit.
Cap everything, all the stats, all the powers. Make sure no-one tries to sneak over it, and, at the same time, make sure no-one is underpowered. It can suck to be the only guy whose attack does three or four dice less than everyone else's.
Make the campaign about the characters, and their individual lives and their lives within the group.
If a player has based his character on a favorite character from a book or tv show, make a plot that mirrors one that happened with that character, but throw a few curves into it.
Have the villains taunt the PCs... "Your powers are weak! You cannot hope to defeat us!" and then, when the PCs are victorious, they can taunt right back.
One thing I hate when I'm playing Champions is when the GM thinks that the PCs have to lose all the time. Sure, they might lose a fight in the beginning when the most powerful villain arrives, but eventually the PCs should prevail.
If the villain is going to get away after being trounced by the PCs, have him acknowledge the defeat... "You may have won this round, heroes, but I'll be back! I will not forget this indignity!"