Estate Law Questions? Ask an Estate Lawyer.
It depends on what kind of title they took it under: Tenants in Common or Joint Tenants with Right of Survivorship. If Joint Tenants with Right of Survivorship, the survivor is the sole owner of the property. The decedent estate does not get half interest in the property--nothing passes to the heirs of the decedent. If Tenants in Common, 50% of ownership passes to the heirs of the decedent.
Whether or not you would pay any inheritance tax would depend on whether your father's estate even has in interest in the property. If the estate does not have any interest in the property, there is no tax due. For more information, click on the link below:
You asked tons of questions, which I am not in a position to answer within the confines of this forum because unlike your Attorney I am not privy to all the facts in the case. Nevertheless, it is prudent NOT to pay any taxes on the property until the title issue has been resolved.