Any individual IP packet can be communicated electrically over cable, as optical signals over fiber, or wirelessly as radio signals.

An IP number is the unique address by which you can reach an individual computer. At least, that was the original idea of IP addresses; if you want to know how this has changed in recent days, do some research on the following topics: IP address exhaustion; private IP addresses; public IP addresses; NAT.

No, MAC addresss and IP address are not the same. MAC addresses are "hard-coded" into the Network Interface Card (NIC) and only ID that individual card. The IP address is software generated and ID's both the network and the individual host.

TCP has no default port. Individual applications - such as FTP, DNS, or Telnet - do have default ports.

As soon as it communicates with a remote server, the server allocates a unique IP address in order to identify the individual computer.