The WoL function is designed mainly designed for, say a machine that is used as an internet gateway (other machines share 1 internet connection) and is turned off, and you want to use the internet from an non-internet connected in another room then you simply boot the machine your at, and the LAN will by virtue of the WoL function wake up the internet gateway to save you having to turn it on. Pure laziness.
Other functions use this feature, but to be honest it isn't really used in the office.
Question 2)
Yes it is possible, but you need to do a lot of messing about, which includes mapping ports and allowing the correct type of request (UDP, HTTP etc).
Do a google search for the best advice.
Hope this helps