If you are on a mac and need to batch rename a lot of files Finder has this function built into the system now: http://osxdaily.com/2015/05/28/batch-rename-files-mac-os-x-finder/
The images sizes (below) are merely Recommendations, you aren't required to follow them. If you want to upload slightly larger dimensioned images or slightly larger file size images you are more than welcome to.
Your website resizes images on-the-fly, so they will fit any size screen, which is super exciting, but means you must take a few special steps to prepare the images you upload.
1. Upload a large image (don't worry we make smaller versions for mobile devices and ipads): Your ideal image size is 1860 x 1140 pixels for a horizontal (930 x 1140 for a vertical). No need to crop your image, just make one of those dimensions the biggest (i.e. 1860 x 1072 or 1700 x 1140).
NOTE: For the 4k and 5k screens people are using now you might consider 2500 x 1700 (horizontal) for sizing your images.
2. Use "Save For Web" in Photoshop or the equivalent in lightroom "File –> Export": You want the images in the 250 - 550 kb range (the less colors the easier it will be to get it lower), so use a lower quality setting to get it down there. When saving for web make sure you include a color profile and XMP so your caption and copyright remains.
This video will help you with image resizing:
Watch this Video to see how to batch resize all your images at once:
3. Name your images properly: Avoid using anything but letters, numbers, underscores and dashes (and only one period before the jpg) when naming your images. Each image must have a unique name.