"and he shall read in it all the days of his life": "the days of his life": the days; "all the days of his life": the nights.
"so that he learn to fear the L-rd his G-d": We are hereby taught that study leads to fear; fear to heeding, heeding, to doing. Because we find that a commoner is like a king vis-à-vis words of Torah, we might think he is like him in other things, (too); it is, therefore, written "to heed all the words of this Torah and these statutes": He is like him in respect to words of Torah, but not in respect to other things,