Question related to the Greek k-perfect

From: alexandru_mg3
Message: 46562
Date: 2006-11-12

Could somebody tell me if the Greek k-perfect is an internal Greek
construction or is originated from PIE times?
What the inner k-particle could mean if from PIE?
And the lead-in vowel -a that characterized the set of its endings?
Also : is the reduplication of the root always mandatory ?
Thanks a lot,
Marius