A: Can I stack more than 3 codes ? - No
Can I change the Dark Web Monitoring frequency? - No, but you can do live scans and decide the frequency you want to do them.
IP count towards Dark Web Monitoring elements, can they be excluded? I mean what if I want just the Vulnerability Scan for my IPs and Dark Web Monitoring for my domains? - They apply to different service categories. You are not forced to monitor IPs on the Dark web service.