בנים אתם לה' אלוקיכם, לא תתגודדו, it is bad manners to display excessive grief over the loss of a relative as long as a more relevant relative (G’d) is still alive. This is why G’d reminds us in this context that we are His children, i.e. that whatever relative we may mourn we have a father who is alive and well so that we are not really orphaned.

ולא תשימו קרחה בין עיניכם על מת כי עם קדוש אתה, there is no reason to mourn excessively for the person who has passed as he, at least, has not experienced any loss, on the contrary, he has been promoted to the region of eternal life, something of which our sages in Avot 4,6-7 have said that a single hour of the serenity experienced in that life is worth all the combined delights ever experienced during one’s transient life on earth.

סגולה מכל העמים, this is why G’d prohibits your disfiguring yourself. He did not prohibit this to the Gentiles, as they are not as special as you are.

לא תאכל כל תועבה; before the Torah had been revealed, given, the Israelites as well as mankind generally were aware of the concepts “pure, טהור,” and “טמא, impure.” This is clear already from G’d’s command to Noach to take into the ark with him one pair each of the “impure” species,” and seven pairs each of the “pure” species of animals and birds. (Genesis 7,2) When G’d, after the deluge, permitted man to eat meat, He did not distinguish between meat from “pure” animals and meat from “impure animals.” However, now, after the giving of the Torah, when the Jewish people had become so special, it was no longer appropriate for them to ingest the remains of impure animals or birds (or even fish). Our sustenance should not be dependent on such inferior living beings. We should remain constantly aware of the gulf between man and beast, especially beasts which had never been suitable as sacrifices.

לא תאכלו כל נבלה, even of the pure species which you may eat after they have been slaughtered ritually.

כי עם קדוש אתה לה' אלוקיך, even though the dead carcass is in a state of being fit for human consumption, such as by strangers in your midst or residents who have not yet converted to embrace all of Judaism’s laws. עם קדוש, ready to achieve the perfection intended for it by its Creator. (this would be slowed down or impeded by eating lower forms of living creatures, not that eating them would be harmful, objectively speaking.)

לא תבשל גדי, as is the custom among the Gentiles who believe that by doing so they will increase the numbers of their livestock (compare Moreh Nevuchim, section three 3,48)

עשר תעשר, for by tithing the crops of the fields and orchards as well as that of your livestock, you will actually increase their numbers (G’d will see to this) instead of decreasing the amount at your disposal. This is what our sages meant when they said in Shabbat 119 עשר בשביל שתתעשר, “give the tithes so that you will be enriched” (with the dot in the letter ש of the word תתעשר on the right hand side.).

למען תלמד ליראה, for the site chosen by G’d for the Temple also houses the Supreme Court, Sanhedrin, from where knowledge and understanding is dispensed.