Say you have done things in the past which others can recollect to you that you have absolutely no memory of, of situations that placed you out of your comfort zone.

Then you remember them months or years later with precise clarity.

Is that a symptom of PTSD?

how can you be sure it´s not suggestion made of the given facts?

That's a weak description, ptsd only happens after "extreme psychological trauma."

Say someone says to you do you remember such and such and you are like what, then later you remember it and ask them about it and your details match.

Ok replace taken out of comfort zone with severe psychological trauma if it suits you.

Is that a sign of PTSD?

It might be, but PTSD is very severe. You might want to read more about dissociation, because that's the only symptom you mention.

1. Have you been diagnosed with PTSD?

2.
If the current symptoms did end up pointing towards a dissociative disorder, PTSD may have been a precursor; unless drugs are involved, in which case he would be in an entirely different ball park.

3. right? I'm not a doctor.