Can I file a divorce from Germany?

Yes, but best to have an attorney as there are specific legal procedures that must be followed, and court dates that must be covered.

Yes, if you're a Texas resident. Presumably your spouse is here in Texas or you're a Texas resident.

If your spouse is a resident of Nevada for 6 weeks or if you are in the military and Nevada is your state of residency you can.

If your spouse still resides in North Carolina and has for the last 6 months (and you have been separated for at least 1 year which is a state requirement), then YES you can actually file for divorce here in NC even though you are in Germany! While you can normally file court documents by mail, even from another country, if you don't have an attorney then you would eventually need to be here to handle the final stages of the divorce including appearing at the divorce hearing itself. But for you, the best option would be to hire a North Carolina to handle it for you in which case you don't even have to go to court.