Converted Christian to Islam Legality of New Marriage

A Filipino married under the Roman Catholic Church changed his religion to Islam years after the Christian Marriage was broken (not legally,nor annulled) and got married to another woman under the Islam religion.

Query:
1. Does their Islam Marriage legal under the Philippine Law?
2. Is the Christian Marriage still legal after the Islam Marriage took place?
3. Will the husband liable for adultery or any other infidelity case?

Thank you and more power.

To get converted into Islam it takes time as there are many processing to do and when granted it protects him from marrying as many as women he wants to marry unless he can support them all financially. Under the law of Islamic marriage in my understanding based on my Muslim friends the man is not allowed without the first Islam marriage wife's approval to marry another woman. If he is married before his conversion, the Islamic religion has to be followed and the christian marriage cannot file a case against him. It is not easy to convert to be a Muslim there is certain stage they have to prove their sincerity in order to embraced Islamic religion. This is not something anyone can used as excused on their polygamous intentions or purposes. Therefore, if he is married before converting, his christian marriage is difficult to pursue as he embraced different religion already. This is based on my friend's experience. Ciao!

yes, on its face
yes, on its face
yes, if it can be proven that he did not convert in good faith