I am concerned for safety with my new gas stove and my microwave above it. Micro does have an outside exhaust fan. How much space should there be between them plus any safety issues I should be aware of. Thanks

Having just done a similar project myself: check the installation instructions that came with your new stove. The typical minimum clearance is 30 inches from the burner to the bottom of whatever is above it, but the instructions should tell you for sure.