precious_moments,
I have been to Avillion Resort, but my family did. They said quite nice. But Pork Dickson is seriously highly polluted, so don't expect that you can play at the seaside, really more for enjoying the facilities at the resort only.
Driving to Malaysia is not that bad lah (unless you drive a luxurious car?). During day time, it's safe, just make it a good habit to ALWAYS lock the door. In Malaysia, can't take things for granted like when you are in Singapore, it's definitely not as safe as here. Just have to be more alert lor, like always keep the valuable out of sight (better don't bring any), avoid to go to quiet places at night, etc. I went to KL with my boy and my tummy a couple of months back, no problem at all.