The tractor that Red repairs is a McCormick-Deering T20 Trac-Trac-Tor. Just over 15000 of these were produced between 1931 and 1939.
Because of the Hays Code, she was wearing a bathing suit in the river, living alone with her father in a very far away place she could have swimming in the nude, like many pre code movies such as Jean Parker in "Two Alone", Barbara Kent in "No man's law" Joan Bennett in "Wild Girl" and in several more.