Q. 1. Is it true that those who pass in front of the Eucharist, they must always genuflect?
A. 1. In the "The General Instruction of the Roman Missal," # 274, it states:
Genuflections and Bows
"A genuflection, made by bending the right knee to the ground, signifies adoration, and therefore it is reserved for the Most Blessed Sacrament, as well as for the Holy Cross from the solemn adoration during the liturgical celebration on Good Friday until the beginning of the Easter Vigil.
During Mass, three genuflections are made by the priest celebrant: namely, after the showing of the host, after the showing of the chalice, and before Communion. Certain specific features to be observed in a concelebrated Mass are noted in their proper place (cf. above, nos. 210-251).
If, however, the tabernacle with the Most Blessed Sacrament is present in the sanctuary, the priest, the deacon, and the other ministers genuflect when they approach the altar and when they depart from it, but not during the celebration of Mass itself.
Otherwise all who pass before the Most Blessed Sacrament genuflect, unless they are moving in procession.
Ministers carrying the processional cross or candles bow their heads instead of genuflecting."
As a general rule, when the faithful enter or leave the Church, they face the Tabernacle and genuflect as an act of humility before the Lord. Whenever they pass the Tabernacle, they must genuflect. And when passing before the exposed Blessed Sacrament during Adoration, they must genuflect.
Note: A genuflection means to bend one's right knee to the floor/ground, without exception or excuses, unless one has a severe medical condition that makes it impossible to do so.
Based on the percentage of those who do bend their right knee to the floor/ground, it appears that most Catholics have a severe medical condition that makes it impossible for them to do so, or in simple English, they refuse to humble themselves before the Lord Jesus, their Saviour.