Hi Andy,
Yes, the sizes listed in the first link are up to date. As to whether you cretae the master size or all sizes, it's up to you. If you just create the master size, it's less work for you. The system resizes the image, which can lead to a very slight delay in displaying it the first time. Thereafter, the resized image is cached and available as needed.
OTOH, if you create all the sizes yourself, you can control the quality of each size and what is shown. For example, you might want one of the smaller sizes to display only part of the larger image.
Bottom line, if it were my community and I had a graphics person at my beck and call (however briefly), I'd do all the images in-house rather than just the master size.
Hope this helps.
...Susan