4. In a speech: some of it was good, but a lot of it was padding. I.e. filling time without saying much that is useful.

Just to add to what's been said: 3. You have to know what 'padding' means if you are a developer who styles web pages with CSS. It comes up often.

1. Exactly. 2. It's acceptable, but sounds less good. We "leave" extra time. 3. No. It would most commonly be used literally, like for protective sports clothing. But a room with "padded walls" is a common metaphor for the type of environment an insane person is kept in. 4. Fortunately his padding protected him from serious injury. People need to take more risks instead of spending all their time in padded environments.