no, but you can do a skype or hangout with who you are playing with while you are playing minecraft with them.
Options > Open to LAN
Yes you can, you need an acess point for both systems
LAN means Local Area Network. LAN World on Minecraft basically means that anyone else playing from the same router/modem as you can join your world.
If you have a cracked client, sure.
A LAN world means if someone is playing Minecraft using the same modem/router as you, they can come into your world and play with you.
LAN means Local Area Network meaning you have a party on your xbox/ps3 which means that the "LAN" party are local players on the same xbox/ps3
To turn an SSP world into a LAN world, click on esc to bring up the menu and click 'Open to LAN'
You can.
LAN worlds are available only to people who are on your local network. They have to actually be connected to your network, for the LAN IP to make sense.
Yes. It doesn't matter if it's LAN I believe. You just have to download some plugins and put it in the plugins server if you're using vanilla minecraft.
No. The way LAN connections work is: Minecraft searches your network (what all computers in your home are connected to) for games to join. Through LAN connections you can't connect to anything outside of your network.
Press escape while playing, and click the button that says "Open to Lan".