Ok, lets get some thing stray. Your laptop/PC has an IP address which it must have to go on any form of networking e.g. internet. Windows XP, Vista, 7 and 8 use it. Changing it is not that hard. But before that know there are 2 IP's out there. IPv4 (Internet Protocol version 4) and IPv6 (Internet Protocol version 6) or MAC (Media Access Control) address (another name for IPv6). Now IPv6 is not easy to set considering you need to know Hexadecimal, use 0-F instead of 0-9. If you do not know how to count from 1-F then just use IPv4. Changing IP go to http://www.wikihow.com/Change-your-IP-Address-(Windows) But firewall is the only way to keep hackers out. That and a good anti-virus. PS. your internet connection has its own IP. That is what gets traced all over the net.
Not easily! The only solution is to change the Network Card on the laptop. The MAC address (I guess you mean physical address by laptop IP) is associated with the Network card. Otherwise, if you are really talking of IP, it could be possible if your ISP has not set it fixed. In such cases you need to contact your ISP or the guy had set up the internet for you in the first place. For dynamic IP though, you can change the IP by simply turning the router on and off.