I'm just getting started with Lightroom 4. I've been shooting RAW + JPG using my Nikon D7000, but would like to just shoot RAW and then convert to JPG in Lightroom. What's the most efficient way to convert a group of files to JPG and end up with approximately the same look and quality that I get out of the in-camera conversion? Does Lightroom apply any processing if I just import all the files and then directly export them to JPGs without changing anything?
You want to import the raw images into Lightroom and then process one image the way you like it using the develop mode. Then select all and hit the sync button on the bottom right. This will create the same effect for all photos that you have synced and is a real time saver. Then, to export, select all images and then go to file > export and follow the dialog box from there.
There are so many different variables on the export (quality, format, etc).
If you do not change anything in Lightroom in the develop mode, then Lightroom will not apply any processing and will therefore make no changes.
You can setup a default profile for Lightroom to apply to newly imported RAWs. You can actually specify this per camera and even per lens (it will pull the info from the EXIF data on the RAW shot).
By default, Lightroom doesn't do a lot of processing. It applies a mild sharpen on export typically, but that's about it. You could certainly make a custom profile that would make an initial pass at adjustments, but a large portion of the reason for using RAW is so that you can make creative decisions about the images rather than having it automatically processed.
If you want to match the image processing the camera does exactly, you generally have to use the software provided by the camera manufacturer for processing RAW files as many of the algorithms used by the camera are proprietary to the particular manufacturer. In some cases, those changes can then be saved into the RAW file and the RAW file can then be opened in Lightroom with some of the changes applied.