Do you think the lawyer was gullible? How would he have avoided being taken for a ride?

Yes, I think the lawyer was gullible. He informed his purpose of coming to New Million to Bill with out knowing anything about bill. He must have behaved cleverly. First he must have enquired about Lutkins without informing his purpose. Secondly he should not have behaved so friendly with an unknown person. Thirdly he should not have such deep faith on bill.