Hi, better off with coated filters on digital as sensors are highly reflective & uncoated tend to 'bounce' the light about, multi is better than single coated but costs more, although I think you would be hard pressed to spot the difference on your FZ18.
Marumi do multi coated high quality filters at good prices & with an easy clean surface too.....try Dave at www.dovercourtphotography.com he usually has a good range at good prices & is a very helpful chap.
UV does what it says & filters out UV rays & makes the picture clearer (reduces haze), skylight is essentially the same but adds a very slight warm cast, sometimes favoured by landscapers & lens protect is clear & does nothing except protect the lens!
Hope the above is useful,
Regards,
Don