Usually but not always. A common insurance scam is to pass a car, cut in just in front of it, then brake hard causing a collision. Dash cams video is a good thing to have to fight this if it happens to you.

No, even then. If a car cuts in front of you, you have at least a few seconds of time to start making space for them, and once they are in front of you, you should immediately make a safe amount of space between you and them.

Yes, in a country where safe driving is not internalized you will inevitable have someone rear-ending you while doing this, but if the options are "accident where you're at fault" and "accident where you're not at fault", pick the latter.