best to get him or her to sign a release. In case one day your photos are valued be it as stock footage or pieces of photographic brilliance, you have yourself covered and you wont have your model suing you for a cut of the fees you are paid later.
Get him to sign a release if you intend to use for commercial purposes, if not, then just do it as good business practice, its always handy to have, but not a necessity if your using the shots for non commercial means. You are not obliged to give him the pictures unless stated in the 'contract', but it may be in your best interest to if you want to work with him again in the future, do him a favour, he might do you one later.
1. Not unless you intend to sell your photos to US based stock agencies. Using it in a commercial context in Singapore does not require any model release as far as the state of law in Singapore at this time is concerned. Those who tell you that you do probably did their "research" by reading US based websites which do not apply in Singapore.
2. You dont have to give anything. You can give if you want to.