What you can and need to do depends on what the photog is willing to do and on the specifics of the processing he used.
Elements 9 and Lightroom 3.x do share the same basic processing "engine" but two things to be aware of:
First, if you are using Windows, the Raw processing toolset is a "trimmed down" version of the tools available in the CS5 and Lightroom 3 Raw processors. What that means it that it is very possible that not all adjustents made in Lightroom will be visible in the Elements Raw processor. I'm speculating here because I don't have Elements to test them out, but it is very possible. If you have a Mac with Elements the newer versions of Elements use the Bridge interface (like Photoshop CS uses and, magically, you can open up Camera Raw from Bridge with the full toolset (if you open the file properly). If you do use a Mac let us know and a Mac user can give you specifics.
The second thing is very important and will require one more step by the photog. If on the CD he gave you you examing the folders with the system file browser and you see the Raw files listed, well, that of course is to be expected, but if that's all you see then you will have a problem. When you work on a Raw file in Lightroom, the program keeps the editing and other information in "metadata" which is stored by default in the Lightroom catalog. It is not written to the Raw file. What this means is that by default if you open the Raw file in any other Raw processor/viewer, any edits you have done will not be viewable or applied to those images.
The way that Adobe "works around" this to make Metadata available to Camera Raw is by providing the command for Lightroom to "Save Metadata to Files", available in different ways in different modules. This creates what is called a "sidecar file" with an .xmp extension that has the same base name as the associated Raw file. It can be done with a batch with selected files. Camera Raw reads those .xmp files automatically, so once you have done this you can get off and running quickly.
Of course, a first question is whether Elemets 9 will be able to handle all the metadata from the photog's edits like I mentioned above, but the obvous big question is as to whether he did that save process at all, and if not, is he aware of the need to do that so that the Raw processing can be shared?
If he did the metadata save, then you are good to go, but if not then it's between you and him to work out what to do -- if he's happy to do the "Save Metadata" operation and then burn you a CD with the .xmp files, then good. If he is unfamiliar with that command, then you might forward to him a copy of this post so he can understand what the "deal" is. He could then search Help with the string "save metadata to file" and quickly get to the section that covers this and presents the various approaches to doing this.
If you can't get those .xmp files, you will be faced with a challenge -- all your wedding shots will open in Elements in their "bare bones" Camera Raw rendering and won't have the processsing done by the photog, which will frustrate you because you won't be able to match the prints he's given you with the ones you do.
If that's the case, the "good news" is that he was still able to get the Raws to you and you can launch into your Raw learning curve with a cool set of shots to learn with and, maybe, even begin to develop your own "style" that may make you quite happy!