All fPeter had do say is, "no matter what never let dad touch you." And pPeter would have his powers still.

I think it's because fPeter came from a future where the events are different from what's happening now. When fPeter time traveled to prevent Nathan telling the truth about people having abilities he changed the course of events (butterfly effect)

Maybe in the future he is from Arthur never steals his abilities? He didn't really get a chance to tell Peter about everything either but he did say "Someone from your time is putting together a formula". Does he even know himself who is behind this?

Yeah, exactly. FPeter screwed everything up. Just as FHiro, I suppose he thought he had figured out how to change it, but clearly it didn't work because no everything is all out of whack.

Future Peter originated from a completely different timeline. He never went through anything Present Peter went through after he changed things.

but he would know his dad was still alive and i am sure that fPeter gets involved in everything just like pPeter. So I am sure he would know his dads power after 4 years of his dad sucking people power.

Peter messed up. Maury and the bad people escaped. Angela told Hiro and Ando to dig up Adam.

Future Peter doesn't know about daddy. In the future FuturePeter came from Arthur was most likely still doing things from the bed. Now he's walking and talking. Oh, Peter sooo messed up.

Well assuming F_Peter knew about his dad. Then I would say the reason he didn't warn P_Peter is because he didn't have the chance, you know with getting killed and that.

I don't think so because as we said, fPeter was from a different timeline with a specific course of events. When he time traveled to change the future he basically changed the whole course of events. So it's completely possible that in fPeter's timeline and story Arthur wasn't still alive

The scar on FPeter's face would coincide with him losing powers temporarily. Maybe FPeter thinks/knows that Sylar's power can beat Papa Petrelli's power but didn't want to give too much away...you know, that whole continuum thing.

No, Arthur is not, directly or indirectly, the cause of fPeter's scar - if he was, then fPeter would have known all about him, and would have told pPeter not to touch him.

In F-Peter's time, Adam would not have been taken to Arthur, he wouldn't have healed, and that wouldn't have happened.

There's a fundamental change that stems from the level 5 breakout. The events up to this point will be unchanged:

1) Hiro receives the message from his father and opens the safe.
2) Daphne, having been recruited by "Linderman", steals that part of the formula from Hiro.
3) Hiro and Daphne intercept the Haitian trading the other half. Hiro is knocked out and taken to level 2, the other half ends up in Pinehearst's hands.
4) Angela tells Hiro to dig up Adam.
5) Hiro digs up Adam.
6) Adam knocks Hiro out and runs off.

Here is where the convergence takes place because Adam only ended up in Arthur's hands because of Knox. In the timeline where the level 5 breakout didn't happen, Knox wasn't there.