Address Website

You can't just hack into someone's computer and get all their stuff just because you have the IP address. In fact, being behind even the cheapest broadband router is typically enough to protect you assuming you don't have DMZ turned on. source

Personally, I've given up on hiding my email address. I find it easier to look into better spam-filtering solutions than worry about obfuscating. You could spend days trying to find the best way to obfuscate your address, and then all it takes is one person to sell your address to a spammer and all that work was useless. source

The MAC address is only present in communication between devices in the same subnet. Once your frames leave your network it will have different data link layer data added. source

IP address can only affect your site if it is associated with a bad neighborhood. Make sure you only purchase a domain from a reputable provider. source

I use a form that people fill out and it gets sent to my inbox. On that form they have to fill in a "human" question. I've had that active for three months now, not a single piece of spam has made it's way to my inbox. source