The Shofar at the Top of the Tree or Across the River

Can you desecrate the holiday to retrieve a shofar at the top of a tree? Can you swim across a river for it? Can you clean a shofar on the holiday and what cleanser can never be used to clean a shofar?

Bonus: A sermon tip to be derived from the latter law.

Text source: Laws of Rosh Hashanah, Shulchan Aruch of the Alter Rebbe #586