No finer tools could be found any place. They were complete; everything needed was here. They had been made of a special material, in the necessary sizes and shapes.

Jimmy convinced the prison that he was reformed, but Ben Price, the police officer, was not convinced. He believed that Jimmy Valentine would return to his life of crime, and go back to cracking safes. He kept a careful lookout to make sure that he would be aware of any of this sort of activity as soon as it happened.

Jimmy kept his tools, and might have gone back to a life of crime. He had not lost his touch. He was able to open the safe to save the little girl. The irony is that he used his criminal skills for a good purpose. Ben Price decided to look the other way, feeling that Jimmy was a good person after all.

Mike Dolan owns a building in an unspecified small town. The building is not described in detail, but since it is a "small town," the building itself must be small. It is probably a wooden building two or three stories high. Mike Dolan runs a restaurant on the ground floor and rents out rooms on the second floor and on the third floor if a third floor exists. Mike is a friend of Jimmy's and has been keeping his room available for him since he was arrested by Ben Price for the "Springfield burglary." Jimmy had been sentenced to four years in prison, but because of his many political connections he had only expected to be behind bars for a few months. Significantly, it took ten months before his friends, including Mike Dolan, could get him a pardon. Things are getting a little tougher for Jimmy Valentine. He is becoming famous as the best safecracker in the business; and so the governor "balked" at giving him a pardon at all. The governor is a politician. He has to worry about the voters. If he pardons a notorious criminal it makes him look bad with the voters. Mike Dolan runs his restaurant as a "front." The place is undoubtedly a hangout for criminals, and Dolan must make most of his income from crooked enterprises. He probably rents his rooms out to many shady characters. All of this is deducible from the following excerpt from the story:

Three hours later he got off the train in a small town. Here he went to the restaurant of Mike Dolan. Mike Dolan was alone there. After shaking hands he said, “I’m sorry we couldn’t do it sooner, Jimmy my boy. But there was that safe in Springfield, too. It wasn’t easy. Feeling all right?” “Fine,” said Jimmy. “Is my room waiting for me?” He went up and opened the door of a room at the back of the house. Everything was as he had left it. It was here they had found Jimmy, when they took him to prison.

Jimmy's main purpose in going back to his old room is to get his suitcase full of highly specialized safe-cracking tools. These tools will play a major role in the story. They will enable him to rescue the little girl trapped in the bank vault but also expose him as an expert safecracker and not Ralph Spencer, the small-town businessman he has been pretending to be. Jimmy moves to Elmore, Arkansas and assumes a new identity. He intends to continue burglarizing banks, but he would like to shake off his name and his reputation, both of which are nothing but a handicap to him. But he falls in love at first sight with Annabel Adams, daughter of the owner of the town's bank, and this changes Jimmy forever.

Jimmy Valentine looked into her eyes, forgetting at once what he was. He became another man.

If you read the text very closely, you can infer some details about Mike and his relationship with Jimmy.  Jimmy was in jail because of a "Springfield job" that he got caught doing.  He was robbing a bank in Springfield and got caught.  After his release from prison, Jimmy goes right to a restaurant and eats, then meets with Mike.  Mike apologizes for not getting him out of jail sooner.  He wasn't able to, he says, because

"we had that protest from Springfield to buck against, and the governor nearly balked."

So, apparently, Mike was the one leading the attempt to free Jimmy from jail; he succeeded too.  Jimmy was supposed to be in there for 4 years and only served 10 months.  So, Mike could possibly be Jimmy's lawyer, not to mention, probably a good friend.  He's involved in the law somehow, to be able to get Jimmy out.  He is probably also corrupt, since he knows that Jimmy is a criminal who is most likely going to steal again.  He asks Jimmy knowingly, "Got anything on?" referring to another theft job.  He is also holding the key to Jimmy's apartment.  So, Jimmy had to meet Mike, as he was the one responsible for getting him out, and also the one who could get him back into his place, where all of his money, safe-busting tools, and clothes were.

I hope that those thoughts helped a bit; good luck!