Yeah... Like Omar says, they move things around and sometimes it might take a minute to find. sometimes they move it to a drop down or even a different location. I remember opening up 5.0 and couldn't find Vector -> Mapping nodes... because Vector had been moved under Utilities. Often, if you just click around, you'll find that what you're looking for has simply been moved. More often than not, things aren't removed unless they're replaced with something better or is something no one else uses anymore because it was based on an old technique that no one uses anymore because better methods have been found to solve the problem.
If I understand it correctly, MultiLayer EXR's are now stored as multiple Image Files, as opposed to Image Files with mulitple layers. This is done, so that other Programs are able to read them. (Again, this is how I interpret it..I am probably wrong.)
When you're interested, you can read about the reasoning behind this here:
