Connecting a iMac and a Macbook

I am a newbie to Mac so I hope that these questions are not to basic.
First what is the best way to share data between the imac and the macbook. A friend told me to get a firewire cable however I am running on a wireless network so presumably I could create a network for the two macs or should I connect via an ethernet cable. I am not looking to move large amounts of data just the best and easiest way.
Second I am looking to buy an external hard disk for data security which I assume I will use with Time Machine. Will a standard usb connected disk be the way to go.
and finally third if I use ical can I sync between the two machines. All the reading I have done talks about isysnc to phones and not other macs.

Ok quest 1 on a LAN you can connect directly thru the Network - in Finder/Go/Network brings up connections available. If you have different Usernames and passwords on iMac and MB it can get a bit tricky which ones to enter - as i recall if on the iMac and connecting to MB use the MB ones.
quest 2 TM does not do bootable backups but does have all historic changes per back up interval. So you can boot off Leopard and copy data to connected Computer. Best for security is Ext HD and use SuperDuper or Carbon Copy Cloner which will allow you to boot from HD thru any other mac.
quest 3 my choice for synching between 2 units is a Mobile Me account, it updates to latest change in bookmarks, mail, address book and ical whenever unit is on line.

If u want some reading on setting up, this here is good nfo.