Moshe said כ חצות bc he didn’t want to leave room for Egyptian mistakes and mockery if they would miscalculate the time.  Or the כ was bc Moshe spoke exactly 24 hrs before.

Dovid refers to himself as a חסיד bc he woke up earlier than most Kings or bc he was humble enough to deal with blood of Niddah to permit women to their husbands and would even check his rulings with מפיבשת.  Dovid was also nervous that he would not merit עולם הבא (dots over לולא) bc sin can take away merits. (So we find with Ya’akov and with the Second beis mikdash)

The middle opinion to say shema only until chatzos is bc Chazal were so concerned ppl would fall asleep and miss shema

There is a dispute if at night there is a need to be סומך גאולה לתפילה. Dispute hinges upon whether there was גאולה at night in mitzrayim. Or whether krias Shema should always be closer to “bed.”

השכיבנו is an extension of גאולה and ה׳ שפתי is an extension of תפילה.

Saying Asheri 3 times a day brings you to עולם הבא bc it has aleph beis and פותח את ידך.

There is no nun is Ashrei bc of the pasuk נפלה ולא תוסיף קום בתולת ישראל.

מיכאל flies in 1, גבריאל in 2, אליהו-4, and מלאך המות 8.

There is an xtra mitzvah to Shema at ones bed unless תלמיד חכם who can recite just a pasuk.