See if there is a local riding/advocacy group that can help you. They should have advice and may know the local laws. They may even have some 'cycle friendly' lawyers you can ask questions of.

Don't mess about with plastic bags etc - just get a water proof camera.

Make sure your camera is easy to use in a panic (if you are not running it the whole time).

Research mounting options for any defensive products (sprays?) so that they are easy and quick to reach. I've seen a few folks here velcro or rubber band them to drop bars etc.

Don't anger the two-legged problems. They are much more unpredictable and dangerous. Keep your cool, know the laws, speak clearly and to purpose (i.e. don't swear or threaten).

Good Luck.

I'm glad I don't have to deal with dogs and idiot owners (just idiot cab and bus drivers...)