Why are there sometimes two options to say Pl.? For example: ptáky, ptáci or pavouky, pavouci?
Ptáky = acc. plural Ptáci = nom. plural
Same with pavouky - pavouci
They all come from same ending -k (nom. singular)
Is this intended as "not expecting to find", "not hoping to find" or simply "not looking for"?
It is the last meaning. The first two would require a subordinate clause because Czech does not use the infinitive that way.