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...
If a domain is already registered, you cannot register it again while someone else holds it. You can check whether the holder is offering it for sale, but they are under no obligation to sell. A domain without a visible website is not necessarily available: it may be used for email or other services.
Alternatively, consider a different name or extension, taking care not to infringe any trade mark rights. If you negotiate a purchase, agree the terms in writing and use an escrow service that protects both parties. A domain reaching its expiry date does not guarantee that you will be able to register it.