1) Got my Labor and approved I-140 from company A.
2)Transfered H1B to company B and got H1B approval for 3 years on basis of approved I-140.
3) I-140 has been canceled by company A since I moved to company B.
4) Can I go back to company A and use my priority date and revoke the cancelation of I-140.
5) Can I go to company C and use the priority date of approved I-140 from company A by filing new labor and I-140.

Is option 4 or 5 better?

6) How long will the H1B valid after the cancelation of company B before I can transfer to company A or C.

7) Will I get my H1B for 3 years or current expiration date with company A or C. Does it depend on new project duration