... борозды не испортит. Is there an equivalent Polish saying?
I searched for an English version (An old ox makes a straight furrow), and then managed to find a Polish one (Stary wół bruzdy nie psuje). Never heard it, and googling it further didn't even explain its meaning to me.
Approximately how old is a horse when you start calling it "stary"?
Sounds like " stary kot"
I don't hear anything like that, although perhaps the male voice is closer to 'kon' than 'koń'.