Transferring content from old mac to new mac

NEVER EVER use wireless it will fail 100% of the time and take weeks to do so, no I am not kidding!

Wi-Fi simply does not have the bandwith to support migrating data from Mac to Mac. I would STRONGLY recommend connecting the old Mac's Time Machine external HD to the new Mac and then launching Migration Assistant. This type of migration at the max will take about 2 hours.

If for some reason you do not have a Time Machine backup from the old computer connect the two then connect the two using an Ethernet cable. A Time Machine backup connected via a USB cable is the preferred method, why because it works 100% of the time and it is the quickest method.

That depends on the speed of your wireless network and how much data you have to transfer.