Payout
I could give her $0 or million dollars, it would have no bearing on the I-864. My payout was a DIVORCE SETTLEMENT. I-864 has nothing to do with divorce. These matters are not related. 3 lawyers told me that today. If she was an American, I would have paid her the same 250, with no I-864 support. Conversely, if I was broke and she was an immigrant, I would have paid her zero dollars in divorce settlement and I would still be paying her monthly per the case law on I-864.
If Bill Gates marries an immigrant, he will be paying her monthly per the case law on I-864. I realize thats an extreme example, but it's true. Even if he gave her a billion dollars, she would be able to collect the tiny amount from I-864. Even if the court ordered Bill to pay a monthly spousal support of a million dollars a month, she would still be able to collect the tiny additional amount from I-864.
Divorce settlement and I-864 support are in no way related. I am not sure how to make the more clear.
Increase amount
The amount would only go up if the person sues me. Nothing is automated. There is no system in place for automatic increase.
10 years
10 years came from the case law. The document stats 40 quarters (10 years). As I have said many times, this has been interpreted by the court to mean I must pay 125% above the living wage for 10 years.
If you want to understand the real world consequences of signing an i-864, look at case law, not just the document.