Yes, your system is still vulnerable against zero-day exploit, especially due to update is disabled by default on some pirate distribution.
And what about a crack (or an activator) that allows you to freely update your software even with a fake key? If my OS remains updated, is it still vulnerable to hacks just because it isn't genuine?
4) No Idea
Sorry for the incomplete statement there.
What I mean is:
What if I have an Antivirus software which is cracked by a software from some website to use its Premium features like adding extra database of all the known viruses from that Antivirus company, even though my Windows is genuine and not cracked?
Everything that's is cracked is not secure, just because it's very common that the cracking files are injected with Trojan horses. So you are infected right after your fresh installation. Try to avoid all the unlicensed software.