On the first point, viz, is it possible by means of the physical sciences to measure spiritual things, I think the answer is tied to the dichotomy of man and how the soul and body relate to each other. Berkhof's discussion on the
Constitutional Nature of Man might be helpful here. But I think the approach is unlikely to succeed, and is definitely impossible with the current understanding of the human body. To use your example, to reduce the body to mass and the breath to energy wouldn't work: air has mass and the body has fat cells which are practically stored energy. If it is true that sexual sin would leave you with less breath or energy, it is also true that asthma and God-ordained marital sexual activity would do the same. To elaborate on
@Jonathan95's point: there is no one-to-one correlation between particular sins and particular effects on the body that can be so precisely defined as to be stated as an equation. I do not understand the point about imagination, idols and reason.
On the second point, I think there's two points to keep in mind. One, this is definitely not about worshippers even under the Mosaic law: it is a particular law for the priests. Cf. Matthew Henry:
21:1-24 Laws concerning the priests. - As these priests were types of Christ, so all ministers must be followers of him, that their example may teach others to imitate the Saviour. Without blemish, and separate from sinners, He executed his priestly office on earth. What manner of persons then should his ministers be! But all are, if Christians, spiritual priests; the minister especially is called to set a good example, that the people may follow it. Our bodily infirmities, blessed be God, cannot now shut us out from his service, from these privileges, or from his heavenly glory. Many a healthful, beautiful soul is lodged in a feeble, deformed body. And those who may not be suited for the work of the ministry, may serve God with comfort in other duties in his church.
And secondly, the only requirement for the body to be a worthy instrument to worship God in this life is in Romans 12:1,
I appeal to you therefore, brothers, by the mercies of God, to present your bodies as a living sacrifice, holy and acceptable to God, which is your spiritual worship [or reasonable service].
It is true that people have disabilities and deformities as a result of sin entering the world, but it is also true that God has promised to rid the body even of these, but this is assured only at Christ's coming when we will be glorified in soul and body, as John says in 1John 3:2 [cf. 1 Corinthians 15:35-57] ,
Beloved, we are God’s children now, and what we will be has not yet appeared; but we know that when he appears we shall be like him, because we shall see him as he is.