MB3 42b: How To Transport Items that you Found on Shabbos (266:12-13); No Tachanun on Erev Shabbos (267:1-2)

What is the halacha if you find a muktzah item on Shabbos? Can you ask a non-Jew to take it for you? Why don't we say tachanun or Al Naharot Bavel on Friday afternoon?