There is no limit on the number of subdomains that can be minted to a domain.
Unstoppable Domains APIs and libraries will not need to be updated. However, apps may want to confirm their code will support the format for subdomains (e.g., "blog.example.crypto")
No, Ethereum domains will need to be migrated to Polygon before they can mint subdomains.
No, Zilliqa domains will need to be migrated to Polygon before they can mint subdomains.
Yes, subdomains can resolve into domain records and IPFS websites like a regular domain name.
Yes, you can configure Reverse Resolution for subdomains, as there is no difference from a regular domain.
Nothing, they remain intact and will be owned by the same address, having the same records.
You need to approve every subdomain created, so if you don't want a subdomain to exist, you can decline to create it. Unstoppable Domains cannot create a subdomain for a domain you hold. Only you can do that.