2.O-1 does not conflict ur previous NIW. However,ur I140 was filed by ur current employer. u have to withdraw it after u work in the comapny. Reapply with help of them ,EB1/NIW/EB2.
3.one excption:if u filed I140/I485 pending over 6 months, u can directly work in that company (with h1b1 transfer, or with applying EAD). and u don't have with draw the NIW. this is called AC21.