Your case is indeed a complicated one!
I'm afraid that point 1, 5 and 6 give direct impression about your Immigration intent even if you don't actually intend to settle in the US.
2 and 3 shouldn't be a problem, though I'm not entirely sure about 4. I mean, how can a company (A) file your H1B Petition when the Client Letter is from company (C). I suggest you to switch to the company which is sponsoring your H1B Visa, fly to US and then decide whether you want to work for company A, B or C...
Please consult with your employer/attorney properly and go with their advice.