He had not consented to their counsel and deed (houtos ouk ēn sunkatatetheimenos tēi boulēi kai tēi praxei autōn). This parenthesis is given by Luke alone and explains that, though a councillor (bouleutēs, Mar 5:43) he had not agreed to the vote of the Sanhedrin. It is fairly certain that both Joseph and Nicodemus were suspected of sympathy with Jesus and so were not invited to the trial of Jesus.
Was looking for (prosedecheto). Imperfect middle. Mar 15:43 has the periphrastic imperfect (ēn prosdechomenos).