Whats the best health insurance for fertility treatments?

Contact HR. This is less a medical question as it is an insurance/benefits question. It depends on where you live, and the available carriers, and what treatments are being considered. F you have insurance, you should contact your benefits department. If you are buying for yourself you might just have to call around, or use an agent.
Depends. There are many different insurances, each with different levels/plans offered, and many with addiitonal riders that is arranged with the company. It is best to explore each option that one's company is offering (if there is a choice). Ideal insurance from a fertility perspective would include ivf coverage or a large cap.