From your description, it appears he may have gained Conditional Lawful Permanent Resident status from his his previous spouse and such status is set to expire next year.
His options will be to proceed with removing the conditions by filing Form I-751 or filing for Adjustment of Status again based on his marriage to you. The financial questions you ask are issues that typically can be resolved through a co-sponsor, if needed. An attorney can guide you through the chosen process and explain to you further all requirements. I strongly recommend you and your husband-to-be consult with an attorney, and considering hiring one to resolve his immigration matter.
Mario S. Zapata, Esq.