I think SQ's relaxed the age threshold. So it may not necessarily be 31. What matters most is you meet the personality and health requirements. In regard to studying flying in the US, there are only 7 accredited flight schools in the US. It does make a difference when applying to the airlines where you got your license from, so choose carefully. An accredited school I know of that is relatively alright in terms of cost is Phoenix East. You may want to check out that school.