Enough to compare, not just one guess. A typical batch gives you several angles or openers so you can pick the strongest, rather than accepting whatever comes out first.

Yes. Once you find a look you like, keep it. Every new brief can reuse the same presenter instead of starting over each time.

Just an idea. One sentence about what you're selling and who it's for is enough to start. You don't need to write dialogue or a shot list.

Yes. The same brief can come back in different formats and lengths, so the same idea works as a feed post, a story, and an ad without rebuilding it from zero each time.