In the Name of God, the Most High
1. It is permissible for you to refer to any Marja who is as knowledgeable as the Marja whom you are following. However, if there is a Marja who is the most learned among all other jurists including the one whom you are following, it is wajib (obligatory) to refer to him for Taqlid. There is no doubt that A’lam (the most learned) is one whose fatwa (verdict) when compared with the fatwas of other jurists will retain its scientific value from the perspective of wise men and women. Such a thing rarely happens. That is why we are always faced with a group of high ranking and leading scholars whom we are allowed to follow.
2. Where there are two equally learned Mujtahids, you can refer to either of them in any jurisprudential issues except for when such an act leads to a definite violation of Shari’ah law. That is to say, you act in such a way that all religious authorities consider it as void and prohibited.
3. The precaution is to follow one Marja in one issue except for when acting upon the verdict of another Marja is in accordance with precaution and it is also considered permissible by the first Marja.
4. The answer is the same as answer 2.