How would you call it?

[thumpferee]

IMO...On the force play at third with the runner beating the throw, the first play was the force out, so you safe him. Now he slides past the bag and now you have a new play on.
Bang him or safe him again, whatever the case may be.
You also asked: Would you approach it different if it wasn't a force play? Depends. Let the play develop and finish. Delay your call, because on that play the fielder probably still has his eye on the runner and an ensuing tag will follow quickly. On the force, usually the fielder will not be looking at the runner, but its not your job to say: "he's off the bag". You may also want to watch the over-slide, it's an illegal slide and you can get him for interference. JMO