I just took a look at the FAQ v 1.5 and there are quite a few changes!!

How do you guys apply these rules? Do you always keep a printed copy of the FAQ next to you and lookup if a card has a change... and do this untill you know all the changes by heart?

I keep the PDF file on my cell phone so that when I forget something I can look it up... Basically same as keeping a printed copy around.

Most of it is clarifications, not actual changes. After a bit of reference and a couple of read throughs most of it seems to be absorbed pretty easily.

I think that keeping it on your phone is the way to go (unless you carry around a tab or netbook) because you can just search the text for whatever you ruling you need.