Check with the credit score agencies to be sure you do not have one. Provide evidence as otherwise available.

How I travel to USA daily or occasionally from Canada to USA, with Canada PR and USA H1B?

You may continue to work and travel to the United States as an H1B as long as you have a valid visa, status and qualifying employment.

You may work on the H1B for your employer who petitioned for you as an H1B until you change status or return to the United States as an FYI.

When can I file for citizenship after being a permanent resident?

4 years and a day since you last broke your residence. I married to a US citizen and residing together 2 years and 1 day since you last broke your...

Immigration question

As my lawyer colleagues indicate your lawyer is correct.

Yes you may invest passively. You may not be employed in any capacity.

Yes you may invest in the stock market.

Is my eligibility category c9?

Yes for adjustment of status use C9.

Can my brother-in-law sponsor my wife for employment based visa for valid business? Are they considered related ?

It would be considered a relative relationship for the perm labor certification process.

Since you are planning on a “new“ Office L there is far more than the substantial investment. As my colleague has noted briefly there is a...