"Deck the Halls" ending
LALALASwitch magazines, maybe
RELOAD [magazines are often mistakenly called clips]One often follows a bullet
ITEM [in a bulleted list] Three less than once
OCHO [in Spanish once
Despite my distaste for foreign words in English puzzles, given the cleverness of the clue, I'd go with it, especially given that OCHO is crossed with easy words. I appreciate that DOS was clued not as "Two in Mexico" but the more clever "Suggested actions
I have a hunch there is a covert theme, but it is beyond me. I see SPERM..., DNA..., and BLOOD...; they're related, but AUTO... it's a prefix for an antibody produced in one's own bloodstream.
SITPAT, even if it can be found in some reference or other, is at best outre. The idiom is "stand pat."
I just realized that there is a tomato in automaton.