5. Well, I guess the original size isn't really important on Flickr.
They seem to have assorted sizes regardless of what the original uploaded size was. I was just wondering if the image in my last post was the largest one available. (Apparently it isn't.)
To get the links for the various sizes (or just the size you want), sign in to your Flickr account and click on the 'Your Photostream' link. Find the picture you want to use and click it. On the page that opens, find the 'Action' menu on the toolbar above the picture (on the left hand side). Click it and choose 'View all sizes' from the drop down list.
You should be able to click on the various size options directly above the picture on that page. Once you have determined the size you want, right click the 'Download' link (e.g. Download the Medium 500 size of this photo - found directly above the size option links) and select 'Save Link As' (or whatever option your browser has to save that link address). Paste the link into a DU3 post and you should get a picture of the size you selected.
For example, the links for the first picture in the OP are: