can you use running shot and then ranged combat expert?

No, the two powers will not work together.

then what is the use man? that really really really stinks

It gives you the option of using a quick shot with extra move. Or lots of damage attack.

Versitility man the spice of life.

The use of Running Shot is to be able to control your position on the board a little better. It can give you extra range at the penalty of gettting closer to your enemies. Imagine someone with a 10 range and a 10 movement. That person has an effective range of 15. Incapacitate, Mind Control, Energy Explosion, Psychic Blast, and Pulse Wave will all work in conjunction with running shot.

Think of RCE as a skilled ability. You would need to be steady to aim and make the EXPERT hit better.