> Do you use the same password on every site?

I use a password I can reconstruct in memory for sites I care about logging in by hand. If I don't, or don't mind resetting my password each time, I just use random garbage + whatever platform password manager is the one active today, with vague hopes that it'll still be there the next time I need to log in.

> How do you deal with data breaches?

Who ever cares about those? I'm yet to hear about anything impactful being released on those. It only matters if you actually do reuse the same e-mail/login and password combinations on both important sites and garbage sites. Which is something you should not. But 2FA and magic links tend to solve that vendor-side, these days.