In this case, is the khula considered one revocable divorce or three irrevocable divorces? And is it permissible to return to each other with a new contract, or is it necessary for her to marry another man?

A khulʿ (divorce at the instance of the wife) is an irrevocable divorce. If it occurs by agreement between the spouses, and the wife gives compensation, and the husband pronounces the divorce or khulʿ, then the court procedures are solely for documentation. The husband may take back his irrevocably divorced wife (by khulʿ) with a new contract, provided this is not the third divorce. The wife who has undergone khulʿ has full control over her affairs, and she may marry another man after her waiting period (ʿiddah) ends. If the husband is an addict, it is advisable to counsel him. If he repents, then praise be to Allah. Otherwise, separation is better, and she may seek khulʿ from him for his neglect of God's rights. If he does not work and causes many problems, the wife has the right to demand maintenance and kind marital relations, and she has the right to seek divorce due to harm, and she has the right to an independent dwelling.