what is the fastest and cheapest way to send small packages by air from China to Israel

It's contradictory. The faster the service is, the more expensive the charge is. If you want to send package in the fastest way, you may use EMS. As I said, it's more expensive than China Post's small packages.

If you send valuable and important things, I suggest you choose EMS. China Post's small package service has no guarantee. Sometimes, it arrives quickly. Sometimes, it takes too long. Both services can be tracked because you will have a tracking number.