These two words have basically the same meaning. You cannot trust in money that you get by taking it from other people. (See: [[rc://en/ta/man/jit/figs-doublet]])
The writer speaks of riches as if they were trees or vines that could bear fruit. Alternate translation: "for they will provide nothing good for you" (See: [[rc://en/ta/man/jit/figs-metaphor]])
Here "fix your heart" is an idiom that means to desire something greatly. Alternate translation: "do not desire them" (See: [[rc://en/ta/man/jit/figs-idiom]])