I completely agree with everything 5LM's said. I too have a "mine" child. I also say no it is not your toy it is my toy and if you don't share I will take it away. I don't really make the kids "share" so to speak. They have to wait until the other child is finished with it and then they get it. There is nothing that drives me crazy more than a child who wants something just because someone else has it. A child who has a specific toy should not be forced to hand it over (share) with another child just because the other child wants it. They are kids, they usually don't play with something long and as soon as they are done with it (usually leave it on the floor) it is fair game.

As for the child crying. I say leave him to CIO. It will take some time but he will learn nap time means nap time. I don't rub any kids backs. Just put them in bed and leave. If they get up I go in and put them back down and repeat if necessary. They need to learn to self soothe.