If someone gives me a jpeg they want edited, and I take it into lightroom and then edit it, how to I exprt it the same size that they sent? Can I create an export action that allows the same size file to be exported each time?
Don't check "Resize to Fit" in the Export dialog (Image Sizing section). This will export the image in the same resolution as the original, provided you did not crop it.
And yes, you can establish an export preset for any combination of settings in the export dialog. Just adjust to the desired settings and click "Add" below the presets list to create a new preset with the current settings.
Europe, Middle East and Africa