I am still waiting for my I-485 approval. If I am terminated or if I resign from my petitioning employer, what will happen to the petition? Am I safe at this stage to look for another employer?

If the I-140 has been approved and you have an adjustment of status application (Form I-485) pending for over 180 days, you would be eligible to move without losing the underlying validity of the Labor Cert/Immigrant petition. Of course, you would use your EAD document to work for the new employer and would have to submit a letter from the new employer assuming the responsibility of providing you with full time, permanent employment. Kindly contact the office to schedule an appointment to review the job profile (must be in the same or similar occupational classification).