To me Answer of Q11 is is that:



Khulafa-e-Rashideen means “the Rightly Guided”. They truly followed in the foot steps of Our Prophet (S.A.W) and became the successors after Him (S.A.W).

The Holy Prophet (S.A.W) once said “Caliphate shall last for 30 years after me, and thereafter Kingship will be established”.

The Four main Caliphs (In Order of Caliphate) were:

Hazrat Abu Bakr Siddique (R.A) (For a period of about 2 years).
Hazrat Umar-e-Farooque (R.A) (For a period of about 10 years).
Hazrat Usman-e-Ghani (R.A) (For a period of about 12 years).
Hazrat Ali Murtaza (R.A).(For a period of about 6 years).
The sum of duration these Khulafas is about 28 years.
Perhapes this is the psychological reason of Why Khulfa e Rashideen called Khulfa e Rashideen.
I do need an acknowledgment from Sir Asif malik if it is or not.