Me being incredibly tired and lazy having only read the last 10 or so posts, i have 2 points to make:
1: Very sad the guitarist was shot and killed. He was a brilliant guitarist, and Pantera had made some excellent tracks.
2: If anyone comes into your house without you inviting them, ANY force is reasonable. Doesnt matter why they're in your house, the fact is that they are without your permission. Personally i'd give a shotgun blast to the kneecap. Will make it impossible for them to walk ever again and that is just about a right punishment for them.
Obviously if it's some random japanese tourist that walks through your front door, probably shouting at them to get out is good enough. Preferably i'd go for a rubber band in the eye