A bit reading can tell you that UV filters have no effect in normal photography, sensors are not sensitive to UV lights and in Singapore the amount of UV is fairly limited. The remaining purpose for UV is to give some people the feeling of protection for their lenses. Another side effect are filter flare and other funny reflections, usually unwanted.
The purpose and function of a CPL is just explained above by Diavonex. Nothing to add.
Multi-Coating is a form of surface treatment for filters to prevent reflections at the glass surface. Multi-coating is better than single coating or even uncoated.
Vitacon is a brand known for it's substandard quaility. Have a look at Hoya for a decent quality level, regardless whether UV or CPL.