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Here are the conditions as to when you can do what
1. If you are primary GC applicant, then you can open your own company but REMEMBER you cannot work for your own company as that voilates H1B (per law). Your wife can work for your company using her EAD but u cannot.
2. If you and your wife have approved EAD, then your wife can start her own company, seek employment or work independently. But you are not eligible to work for her company either, as you need to be employed with your(or any) employer for your H1B and for your I-140/I-485.
3. If you have approved I-140 and EAD, then you still need a employer and have to remain in your current profession till you get your I-485/GC approved and stamped. IRS watches your financials so you can act smart but they will come back saying "Gotcchaya" with big fines.
Best option is let your wife seek employment or work independently and you taking responsibilty of home till the time you get your GC without much risk. This way you can support your wifes Medical as dependent and she can earn independently for your better living.
Be careful and thoughtful when you plan of starting your own company under your wife's name. Open a Incorporation, this way you are safe from liabilities just in case, if somebody sues your company. Remember CPA and Lawyers and not cheap unless you have a good professional network to get your things done in cheaper and right way. Make sure you are pretty good at accounting or can afford a bookkeeper (Min $8 per hour) to keep your accounts up-to-date else... year end and tax filing could be a hell lot of work for you and may end up spending lots of $$$ to get thru clean from IRS. Keeping records for bunch of years is also important as IRS can comeback in three years to kick your butt again.
Well objective is not to discourage you, but to make you aware and make you smarter and work harder towards forming a better company for you and everybody else working for you. I hope you don't want to form another desi company....like the one you have known from your past.
NOT A LAWYER, NOT A CPA - USE INFORMATION AT YOUR RISK
Disclaimer: I am just a member of this forum. I encourage all to verify facts with an immigration lawyer before making any decision