Line 3. Gui: the "ghosts": literally 'Devil's people', they lived across the Zhou border and often annoyed them. (For the Gui probably the Zhou were the devils).
Line 4. ' Frayed silk have clothes (wear) rags'... Wilhelm translates 'The finest clothes turn to rags'. Ru can be frayed silk or a plug, so "plug a leak with rags" is another way to translate this line. I leave the decision to the reader.
Line 5. The Yue sacrifice is a spring offering, a small one, because there was not much yet to offer.