do you have to stay next to someone to use shield?? i didn't think it was like enhancement. me and friend played yesterday and he said you have to stay next to the person. i've never played like that before but i could be wrong. am i???

You are.

From the PAC:
"S.H.I.E.L.D.™
When a friendly character makes a ranged combat attack, you can give any number of friendly characters adjacent to the attacker and using the S.H.I.E.L.D. team ability either a free action or a power action (but not both) before making the attack roll: For each character given a free action, modify the attacker’s range by +1; for each character given a power action, modify the attacker’s damage value by +1."

Hmmm, which part of "you can give any number of friendly characters adjacent to the attacker and using the S.H.I.E.L.D. team ability either a..." isn't that clear?

i always thought you had to start next to the person and then you were good. i didn't think it worked just like enhancement where you needed to stay adjacent. thanks for being a d bag though.

S.H.I.E.L.D.™ When a friendly character makes a ranged combat attack, you can give any number of friendly characters adjacent to the attacker and using the S.H.I.E.L.D. team ability either a free action or a power action (but not both) before making the attack roll: For each character given a free action, modify the attacker’s range by +1; for each character given a power action, modify the attacker’s damage value by +1.
this being stated, can the power action be for something else but cause the shield team ability?

It's when making the attack roll, so, if the figure was next to you after the move part of a running shot, or at the time of the attack during a HSS run, then it could be used, but, if the HSS fig is carrying the SHIELD member, it couldn't be used. Also, if the figure is carried during the running shot, they could not be given a power action.

Nope.
The S.H.I.E.L.D. team ability doesn't have a wording à la Blades/Claws/Fangs ("when this character is given a [power] action..."), but a plain old "give this character a power action...".

No, power actions can only be used to activate a single effect. Just like you could not give a power action to activate charge and CCE at the same time, you cannot give a SHIELD member a power action to activate say RCE and the TA at the same time.