1: accessing other websites and other network services can be leveraged by an adversary for command and control or for data exfiltration during a breach. (And some of the other apps and tools that can be involved with those other ports and services can themselves be vulnerable to exploits and a potential means of ingress.)
2: You’ll need to discuss that with Vercel support. Depending on the current hosting details, you may be headed for a dedicated host, which is prob preferable here anyway.
Topic:
App & System Services
SubTopic:
Apple Pay