Surge protectors offer little comfort and are not helpful as normally the first time a electrical surge hits them they are good for the bin.

Ask telstra to install network surge protection at your network boundary ie the part of the phone line that connects from telstras infrastructure to your infrasatucture on your house.I am not sure what these cost though but it never hurts to ask.

Norton have told you wrong.The best thing to do in an electrical storm is turn the modem off and unplug it.Why you would lose the norton antivirus I am not sure and makes no sense to me why this would happen.If this is the case I would seriously think about changing your antivirus.

I hope this helps a little

Dave