Your not the first person to overstay, but never advisable to do, but you will have to pay the fine at the airport as others have said 500 a day. Then you will be in the hands of the immigration officer when you return, would be my guess.
Well if that's a serious question? then they are 2 seperate things lol first you need to get a retirement visa and then get a multi entry permit lol then you can re-entry as many times as they both valid for lol.
yes have to agree never been asked. But last trip with Singapore Airlines, guy in front of me only had one way and they advised him he needed a return ticket. So you just never know.
no such rule lol. Never believe what you read from secondhand websites. Believe what is actual facts and from a official website or even better when it's published in the Royal Gazette.