EAD

I am on a H-1B Visa for past 9 years and have EB3 I-140 (2008 Priority Date) from Company A and EB3 I-140 from Company B (2014 Priority Date). I am now with Company C. I am Heart Patient and was operated for Heart By-Pass Surgery in 2013 and since then taking my regular Medicines (for my entire Life). I feel stressed on continually working for 40 hours a week and feel getting a EAD will be a god's gift and I can use this EAD to work at my convenience.

I am on H1 Visa, my H1, wife's H4 and H4 EAD expires on 7/18/2017. I will be completing my 6 years by 7/18/2017. My I-140 is approved. I have a question
1. Should I file for H4 EAD extension along with my H1 and H4 extension
2. Can my spouse (H4-EAD) work while her extension in progress?

My wife has received her L-2 visa. She plans to continue with her US branch of her India employer once she lands in the US and gets her EAD. However for the period while she is US waiting for her EAD to come in, can she continue to be employed with her employer in India and keep receiving paychecks in India, while technically not working for any US based employer prior to getting her EAD?

1. With my approved I-140 from Company B can Company C use that to file my extension for 3 years. I have a copy of approved I-140. Is it safe to change companies in the 6th year. <br>
2. Using the approved I-140, I have filed H4-EAD for my spouse in Feb 2017 and is yet to receive the EAD approval. If I get it will be only valid till Nov 2017 based on current I-797 validity. So, if H1-B is approved for Company C, can I file extension of H4-EAD 120 days before validity based on that approval. If EAD is provided, it is going to expire on Nov 2017 based on the H1-B's current I-797.<br>