Yes it will likely be difficult given information provided.

The case will need to be transferred to a waiver based filing once divorce is final.

Yes you should bring your original BC to interview.

Neither should impact the other given nature of visas.

Best to consult with a family law attorney.

More information is needed about her status and your nature of entry into the US.

No you can leave this blank given status.

For case preparation and strategy, best to work with an attorney or review the I129F form instructions for guidance.

Best to work with an attorney for guidance.

If the marriage is legal in Canada, the US will recognize this as legal.