Q. 1. What is the Catholic approved practice after receiving Holy Communion? Should one bow or make the Sign of the Cross?
A. 1. I am not aware of any written practice that should be applied after one receives Holy Communion.
The teaching of the Catholic Church states that one may receive Holy Communion in the hand or on the tongue, while standing or kneeling. Having said this, it is important to keep in mind that one's practice after receiving Holy Communion should not interfere with the moving forward of those who are receiving the Eucharist.
Those who are receiving Holy Communion can make the Sign of the Cross while returning to their pew without interfering with the flow of the communicants. This would be the recommended practice.