Dear Dr. Thomas Joseph,
Regarding the entry of a priest to the Holy Sanctuary, you asked a question that, why a priest cannot start moving up with his right foot first. The answer is, it is our tradition to start everything with left and end up with right. Remember when we draw the cross on ourselves, we do the same. When the priest wear the holy vestments like the "msone" (ceremonial shoes - *cheruppu*), "zende" (sleeves -* kaiyyura*) etc. the left one is worn first. Furthermore, when the priest take a turn in the sanctuary ( for incensing, shubkono etc.), he take an anticlockwise sequence, i.e., starting with left side and end up at the right side. I think these symbolizes the process of Christ reforming us 'the children of left' (of the evil) to 'the children of right' (of the Divine).
Kasheesho Bennet Kuriakose