Bottom Line:
Income – Anyone that gambles will lose money. Short term, long term or both. Affiliate income based on % of player losses is better overall.
Links – It is a new world. Do not buy them or sell them. Only trade them if you know the person.
USA Affiliate program – Since you brought it up first, Affiliate Edge is OK. Start with one prgram. If you ‘get along’ stay with them. But be ready to change at a moments notice if you need to change links due to industry or program changes (like moving into or out of markets, code system changes updates etc.). Add more later if you want to once you know more.
SEO Google – Play fair and hope to be treated the same.
Good Luck!