US Citizenship documentation,

Best to refer to USCIS form instructions for clarity.

Can I get a divorce while still in the process of doing my wife’s green card?

Yes you may and withdraw the petition you filed on her behalf.

Yes she should be able to apply with the embassy. Contact the embassy to learn more.

The green card and valid passport are sufficient for reentry.

It is best to have an attorney review the criminal documents to better assist.

Yes if you are working with previous employer.

Yes you may but better to wait for it to be requested.

Can I travel to my home country with my I-551 stamp?

Yes you may travel with the I-551 stamp.

Immigration: What to do when I485 denied?

I agree with my colleague - it depends on the basis for denial. Discuss with an attorney to explore options.

Will the money order be accepted?

It will likely be accepted as you have indicated.