You can register .ro domains and every Romanian extension (.com.ro, .info.ro, .org.ro, .store.ro and more), plus international ones such as .com, .net, .org, .e...
The record type depends on the address you received: A is for IPv4, while AAAA is for IPv6. You do not need both if your provider supplied only one address. Also ask which hostname the record should apply to, such as your main domain or a subdomain.
Make the change with the service managing your domain’s authoritative DNS zone, which is not necessarily your domain registrar. Before saving, check existing records for the same hostname. An outdated AAAA record can send visitors using IPv6 to a different server, even when the A record is correct. Leave email records unchanged unless there is a specific reason to update them.