"And take for the unclean from the ashes of the burnt sin offering."
We can explain this according to the prayer "and my soul should be like ashes to all", that it should be the most simple element, that is stepped upon by everyone. Also, plants can grow from soil. This means that everything should grow from me. This is the meaning of take for the unclean from the ashes, that everyone should consider me like ashes to be taken from everything. This is the main reason for burning the sin offering, which means the sins. And put living waters in it, that the Torah is called "living water", that G-d gives him if he is like dust. Then the Torah will be like living waters that flow and go within, so he will be a fitting vessel to receive.
(Divrei Binah - Parshas Chukas p. 113)
"Therefore it says in the book of the wars of the L-RD"
The Talmud says "I created the Yetzer Hara, and I created the Torah as an antidote", therefore "it says in the book", book refering to the power of the Torah, through this you can fight the "wars of the L-RD", meaning that the Torah is the way to fight against the Yetzer Hara.
(Divrei Binah - Parshas Chukas p. 116)