Passport
I, indeed, know the answer to this one.
DO NOT, repeat, DO NOT try to get into Singapore with less than 6months left on your passport!!!
United issued me and my wife a ticket. However, when we got to the airport to go, they would not let us on the plane. In fact, we couldn't even get past the check in desk. I demanded to see a supervisor, and again was told that we were SOL.
So unless United is just a stickler about this, I wouldn't even try it...on any airline!
We were able to get new passports the same day...not an easy proposition, but still missed the flight. We were booked the next day, and did complete the trip, but I can categorically tell you that at least UA will not let you on the plane, unless there is 6 months left on your passport as of the return date.
Good luck. But get a renewed passport...it will save you much grief.
wwbgd