Answer:
d? I don't know to lazy to make Algodoo
They are required to have legally acquired evidence
They are required to have a warrant of arrest
I am unsure of the third. However, it could be that a witness (aside from the victim and/or officer) was present.
Mice are shy creatures who try to, at all costs, avoid trouble. Lennie is scared to talk to others because he's scared he'll get himself into trouble. Lennie is oblivious to what's going on around him, it's as if he's in his own little world.