Each pup is different, you may want to start by leaving him out on short trips out and than lengthen them to see how he handles it. Than have a few sleep overs out of his cage at night and see how he handles it.
If he fall back into behavior you dont like than use the cage again. Wait a few more weeks and try it again. Once you are certain that he can stay out of trouble and not go potty on the floor when you are gone or asleep than you have mastered cage training!
And "yes' I would definitely have the dew claws removed. Your breeder should have had them done as a new born. Better to prevent injury later on. You just never know what could happen. Its very painful if they get caught up on something.