Both questions are similar but different.

Agent Kallus: does his ability only effect the ship he is on? Or does my fleet gain his ability. I have seen people use it both ways and need to know for sure

Omega ace: when he target locks a ship does the no modifie dice affect this ship as it shoots and gets shot by omega ace or anyone in your squad? So if I target lock an xwing can this xwing then shoot at a different target such as Vader and still modify its dice and when Vader shoots back at the xwing can the xwing then modify its defense dice?

Both questions are similar but different.

Agent Kallus: does his ability only effect the ship he is on? Or does my fleet gain his ability. I have seen people use it both ways and need to know for sure

Omega ace: when he target locks a ship does the no modifie dice affect this ship as it shoots and gets shot by omega ace or anyone in your squad? So if I target lock an xwing can this xwing then shoot at a different target such as Vader and still modify its dice and when Vader shoots back at the xwing can the xwing then modify its defense dice?

Only the ship Agent Kallus is on can utilise his ability.

Page 2 of the Rules Reference

I think you mean Omega Leader here, and if he has a target lock on the X-wing, it cannot modify it's dice if it attacks Omega Leader or when Omega Leader attacks the X-wing. If the X-wing attacks Vader, it's free to modify it's dice as usual.

Also worth to note that if the X-Wing instead was Soontir, and the player also had Palatine on his side (say in a Shuttle), then the result of the attack or defense done by Soontir on/from Omega Leader can be modified by Palpatine (since he is on another ship).

Archie

Also worth to note that if the X-Wing instead was Soontir, and the player also had Palatine on his side (say in a Shuttle), then the result of the attack or defense done by Soontir on/from Omega Leader can be modified by Palpatine (since he is on another ship).

Archie