Hello. I am a little new here and have never had a charge off, but I will help as much as I can.
In order to attemt to and possibly get negative items removed, you will need to dispute them. A widely reccomended way to dispute items is to write letters to the big 3. Sample dispute letters can be found
Here
In reference to your question regarding the removal of old addresses, let's say tou incurred a debt wile living in Minnesota. After moving to South Carolina and updating to your new address with the big 3, you get your old addresses, names and phone number removed. So when you dispute the old debt from Minnesota, it may be harder for them to match you up with the debt, so I think that is why it is a good idea to remove them. ( I could be wrong though ) They serve no positive purpose anyhow. A creditor may see you as a risk if you move a lot.
In reference to your question regarding the SoL, I wish I knew more about it since you are currently living outside the U.S. I think they can chose between the state where you signed the contract and the state you currently live in.
Cheers.